BIOGRAPHICAL SKETCH Laurent JC. TAUPENOT, Ph.D. ltaupenot ...

BIOGRAPHICAL SKETCH
Provide the following information for the key personnel and other significant contributors in the order listed on Form Page 2.
Follow this format for each person. DO NOT EXCEED FOUR PAGES.
NAME
Laurent JC. TAUPENOT, Ph.D.
eRA COMMONS USER NAME
ltaupenot
POSITION TITLE
Associate Professor
EDUCATION/TRAINING (Begin with baccalaureate or other initial professional education, such as nursing, and include postdoctoral training.)
DEGREE
INSTITUTION AND LOCATION
YEAR(s) FIELD OF STUDY
(if applicable)
University of Burgundy, Dijon, France A.Sc. 1987 Chemical & Natural Sciences
University of Burgundy, Dijon, France B.Sc. 1988 Cell Biology & Physiology
University of Burgundy, Dijon, France M.Sc. 1989 Physiology
Univ. Louis Pasteur, Strasbourg, France Post.Grad (DEA) 1990 Molecular & Cellular Biology
Univ. Louis Pasteur, Strasbourg, France Ph.D 1995 Molecular & Cellular Neurobiology
University of California at San Diego Fellow 1995-01 Chromaffin Cell Biology
A. Positions and honors
Position and Employment:
1989. Undergraduate student. Dept. of Physiology, University Louis Pasteur, Strasbourg, France.
1989-1990. Graduate student. Laboratory of Ontogenic Neurobiology-CNRS UPR 417, University Louis Pasteur,
Strasbourg, France.
1991-1995. Ph.D. Student. Institute of Biology of Cellular Communication-INSERM-U338, University Louis Pasteur,
Strasbourg, France.
1993. Visiting Research Fellow. Dept. of Physiology, University of Bergen, Norway.
1995-2001. Postdoctoral Fellow., Dept of Medicine, UCSD and VA-Medical Center, La Jolla, CA.
1995-2001. Postgraduate Researcher. Dept of Medicine, UCSD and VA-Medical Center, La Jolla, CA.
1999-2001. Project Scientist, Veteran Medical Research Foundation, San Diego, CA.
1995-present. Research Biologist. VA San Diego Health Care System, San Diego, CA.
2001-2003. Assistant Research Biochemist (Faculty rank), Dept of Medicine, UCSD, La Jolla, CA.
2003-2008. Assistant Professor of Medicine, Dept of Medicine, UCSD, La Jolla, CA.
2008-present. Associate Professor of Medicine, Dept of Medicine, UCSD, La Jolla, CA
Other experience and Professional activities.
Member: The American Society for Cell Biology, The National Kidney Foundation. The Moores UCSD Cancer Center-
Cancer Biology Program, The Catecholamine Club.
Reviewer for Journals: J Clin Invest (1999, 2003), Mol Pharmacol (2000, 2001), Neuroscience lett. (2002), Can J Physiol
Pharmacol (2002), FASEB (2002, 2008), Exp Neurol (2003), Mol Brain Res (2003), Neurosignals (2004), Regul Pept
(2004-2006), Curr Med Chem - Immunology, Endocrine & Metabolic Agents (2004), Trends Biochem Sci (2004), FEBS
Letters (2005, 2005, 2005, 2006, 2007), Physiol Genomics (2006), Dev Comp Immunol (2006), Arterioscler Thromb Vasc
Biol (2006), J Biol Chem (2007), AJP: Heart and Circulatory Physiology (2007), Biochemistry (2007), J Neurochem
(2008), Annals Medicine (2008), J Neurosci (2008), Mol Cell Biol (2008). Grant Reviewer. Ad hoc reviewer National
Medical Research Council, Singapore (2004-2005), Ad hoc reviewer AIRC Italian Association for Cancer Research
(2005), Ad hoc reviewer, Netherlands Organisation for Scientific Research (NWO Dutch Research council), 2006. Ad hoc
NIH/CSR study section member: Synapses, Cytoskeleton and Trafficking (SYN) (06/2005, 02/2006, 06/2008) and
Molecular and Cellular Biology of Neurodegeneration (MCBND) (06/2008)
Honors and Awards: Scholarship award, French Ministry of Education and Research (1990). Master (1989), Bachelor
(1988) and Associate (1987) degrees received cum laude. Predoctoral Fellowship Award, French Direction des
Recherches Etudes et Techniques (DRET)/ Centre National de la Recherche Scientifique (CNRS) (1991). Doctoral
degree received summa cum laude with the congratulations of the Board of Examiners (1995). Postdoctoral Fellowship
Award, The American Heart Association (1996, declined, to accept NKF award). Postdoctoral Fellowship Award, The
National Kidney Foundation (1996). Young Investigator Award, 9th International Symposium on Chromaffin Cell Biology,
Sapporo, Japan (1997). Research Scientist Development Award (1K01DK59628), NIDDK (2001). Postdoctoral Fellowship
Award, The National Kidney Foundation (1998). MERF scholar, Medicine Education and Research Foundation, San
Diego (2003). Research Scientist Development Award (2K01DK59628), NIDDK (2004). Research Project Grant R01
DK067969-01A1, NIDDK (2005), American Heart Association Grant-in-Aid (0855181F, 2008-10)
Conference Chair: Session Chair, 11 th International Symposium on Chromaffin Cell Biology (ISCCB), San Diego, CA
(2001. Session Chair, 14 th International Symposium on Chromaffin Cell Biology, Sestri-Levante, Italy (2007).
Invited speaker: 10th ISCCB, Bergen, Norway (1999); 11th ISCCB, San Diego, USA (2001). 12th ISCCB, La Palma,
Spain (2003); International Society of Neurochemistry/European Society of Neurochemistry Pre-Meeting Satellite, Solden,
Austria (2005), 13th ISCCB, Pucon, Chile (2006). 14th ISCCB, Sestri Levante, Italy (2007). Neuroendocrine Oncology

Seminar, Uppsala University Hospital, Sweden (2007). Cell Biology Seminar, Texas A&M, College Station, TX (2007).
Cell Biology seminar, University of South Florida, FL (2008).
Board member: Councilor to the Board, Catecholamine Club (2007-present)
B. Publications
1. Bader MF, Taupenot L, Ulrich G, Aunis D, Ciesielski-Treska J (1994). Bacterial endotoxin induces [Ca2+]i transients
and changes the organization of actin in microglia. Glia 11:336-344
2. Taupenot L, Remacle JE, Helle KB, Aunis D, Bader MF (1995). Recombinant human chromogranin A: expression,
purification and characterization of the N-terminal derived peptides. Regul Pept 56:71-88.
3. Strub JM, Garcia-Sablone P, Lonning K, Taupenot L, Hubert P, Van Dorsselaer A, Aunis D, Metz-Boutigue MH (1995).
Processing of chromogranin B in bovine adrenal medulla. Identification of secretolytin, the endogenous C-terminal
fragment of residues 614-626 with antibacterial activity. Eur J Biochem 229:356-368
4. Laeng P, Bouillon P, Taupenot L, Labourdette G (1995). Long-term induction of an aldose reductase protein by basic
fibroblast growth factor in rat astrocytes in vitro. Electrophoresis 16:1240-1250
5. Taupenot L, Ciesielski-Treska J, Ulrich G, Chasserot-Golaz S, Aunis D, Bader MF (1996). Chromogranin A triggers a
phenotypic transformation and the generation of nitric oxide in brain microglial cells. Neuroscience 72:377-389
6. Aardal S, Aardal NP, Larsen TH, Angeletti RH, Stridsberg M, Taupenot L, Aunis D, Helle KB (1996). Human
pheochromocytoma: different patterns of catecholamines and chromogranins in the intact tumour, urine and serum in
clinically unsuspected cases. Scand J Clin Lab Invest 56:511-523
7. Tang K, Wu H, Mahata SK, Taupenot L, Rozansky DJ, Parmer RJ, O'Connor DT (1996). Stimulus-transcription
coupling in pheochromocytoma cells. Promoter region-specific activation of chromogranin A biosynthesis. J Biol
Chem 271:28382-28390
8. Mahata SK, O'Connor DT, Mahata M, Yoo SH, Taupenot L, Wu H, Gill BM, Parmer RJ (1997). Novel autocrine
feedback control of catecholamine release: a discrete chromogranin A fragment is a non-competitive nicotinic
cholinergic antagonist. J Clin Invest 100:1623-1633
9. Taupenot L, Mahata SK, Wu HJ, O'Connor DT (1998). Peptidergic activation of transcription and secretion in chromaffin
cells: cis and trans signaling determinants of Pituitary Adenylyl Cyclase-Activating Polypeptide (PACAP). J Clin
Invest 101: 863-876
10. Ciesielski-Treska J, Ulrich G, Taupenot L, Chasserot-Golaz S, Corti A, Aunis D, Bader MF (1998). Chromogranin A
induces a neurotoxic phenotype in brain microglial cells. J Biol Chem 273:14339-14346
11. Kong C, Gill BM, Rahimpour R, Xu L, Feldman RD, Xiao Q, McDonald TJ, Taupenot L, Mahata SK, Singh B,
O'Connor DT, Kelvin DJ (1998). Secretoneurin and chemoattractant receptor interactions. J Neuroimmunol 88:91-98
12. Tsigelny I, Mahata SK, Taupenot L, Preece NE, Mahata M, Khan I, Parmer RJ, O'Connor DT (1998). Mechanism of
action chromogranin A on catecholamine release: molecular modeling of the catestatin region reveals a betastrand/loop/beta-strand
secured by hydrophobic interaction and predictive of activity. Regul Pept 77:43-53
13. Mahata SK, Mahata M, Yoo SH, Taupenot L, Wu H, Aroda VR, Livsey CV, Taulane JP, Goodman M, Parmer RJ,
O'Connor DT (1998). A novel, catecholamine release-inhibitory peptide from chromogranin A: Autocrine control of
nicotinic cholinergic-stimulated exocytosis. Adv Pharmacol 42:260-264
15. Taupenot L, Mahata SK, Wu H, Tang K, Mahata M, Parmer RJ, O'Connor DT (1998). Peptidergic stimulustranscription
coupling in chromaffin cells: regulation of chromogranin A gene expression by the neurotransmitter
pituitary adenylyl cyclase-activating polypeptide (PACAP). The Adrenal Chromaffin Cell: Archetype and Exemplar of
Cellular Signaling in Secretory Control", p 249-259
16. Soriano JV, Pepper MS, Taupenot L, Bader MF, Orci L, Montesano R (1999). Chromogranin A alters ductal
morphogenesis and increases deposition of basement membrane components by mammary epithelial cells in vitro.
Biochem Biophys Res Commun 259 :563-568
17. Taupenot L, Mahata M, Mahata SK, O'Connor DT (1999). Time-dependent effects of the neuropeptide PACAP on
catecholamine secretion: stimulation and desensitization. Hypertension 34:1152-1162 (corresponding author)
18. O'Connor DT, Mahata SK, Taupenot L, Mahata M, Livsey-Taylor CV, Kailasam MT, Ziegler MG, and Parmer RJ
(2000). Chromogranin A in Human Disease. Chromogranins: functional and clinical aspects; K.B. Helle & D. Aunis,
Editors; Kluwer Academic/Plenum Publishers; New York, London, Dordrecht, Boston, Moscow. Adv Exp Med Biol
482:377-388
19. Parmer RJ, Mahata SK, Jiang Q, Taupenot L, Gong Y, Mahata M, O'Connor DT, and Miles LA (2000). Tissue
plasminogen activator and chromaffin cell function. Chromogranins: functional and clinical aspects; K.B. Helle & D.
Aunis, Editors; Kluwer Academic/Plenum Publishers; New York, London, Dordrecht, Boston, Moscow. Adv Exp Med
Biol 482:179-192
20. Mahata SK, Mahata M, Livsey Taylor CV, Taupenot L, Parmer RJ, O'Connor DT (2000). The novel catecholamine
release-inhibitory peptide catestatin (chromogranin A344-364). Properties and function. Chromogranins: functional
and clinical aspects; K.B. Helle & D. Aunis, Editors; Kluwer Academic/Plenum Publishers; New York, London,
Dordrecht, Boston, Moscow. Adv Exp Med Biol 482:263-277
21. Taylor CV, Taupenot L, Mahata SK, Mahata M, Wu HJ, Yasothornsrikul S, Toneff T, Caporale C, Jiang Q, Parmer RJ,
Hook VY, O'Connor DT (2000). Formation of the catecholamine release-inhibitory peptide catestatin from

chromogranin A: determination of proteolytic cleavage site in hormone storage granules. J Biol Chem 275: 22906-
22915.
22. Taupenot L , Mahata SK, Mahata M, Parmer RJ, O'Connor DT (2000). Interaction of the catecholamine releaseinhibitory
peptide catestatin (human chromogranin A352-372) with the chromaffin cell surface and Torpedo
electroplax: implications for nicotinic cholinergic antagonism. Regul Pept 95:9-17 ( corresponding author)
23. Taupenot L , Mahata M, Mahata SK, O'Connor DT (2000). Regulation of chromogranin A transcription and
catecholamine secretion by the neuropeptide PACAP. Chromogranins: functional and clinical aspects; K.B. Helle & D.
Aunis, Editors; Kluwer Academic/Plenum Publishers; New York, London, Dordrecht, Boston, Moscow. Adv Exp Med
Biol 482:97-111 ( corresponding author)
24. Jiang Q, Taupenot L, Mahata SK, Mahata M, O’Connor DT, Miles LA, Parmer RJ (2001). Proteolytic cleavage of
chromogranin A (CgA) by plasmin: selective liberation of a specific bioactive CgA fragment that regulates
catecholamine release. J Biol Chem 276:25022-25029
25. Taupenot L and O'Connor DT (2002). Chromogranins/secretogranins. Encyclopedia of Molecular Medicine,
Thomas E. Creighton, Editor; John Wiley & Sons, p 772-778. ( corresponding author)
26. Taupenot L , Harper KL, Mahapatra NR, Parmer RJ, O'Connor DT (2002). Intracellular protein trafficking into
catecholamine storage vesicles: novel chimeric photoproteins visualized by deconvolution fluorescence microscopy.
Ann N Y Acad Sci. 971:262-265 ( corresponding author)
27. Vaudry D, Taupenot L. Fast-breaking results on the PACAP/VIP/secretin peptide family in chromaffin cells (2002).
Ann N Y Acad Sci. 971:460-466
28. Ulrich G, Ciesielski-Treska J, Taupenot L, Bader MF. Chromogranin A-activated microglial cells induce neuronal
apoptosis (2002). Ann N Y Acad Sci. 971:560-562
29. Jiang Q, Yasothornsrikul S, Taupenot L, Miles LA, Parmer RJ (2002). The local chromaffin cell plasminogen/plasmin
system and the regulation of catecholamine secretion. Ann N Y Acad Sci. 971:445-449
30. Taupenot L , Harper KL, Mahapatra NR, Parmer RJ, Mahata SK, O'Connor DT. Identification of a novel sorting
determinant for the regulated pathway in the secretory protein chromogranin A (2002). J Cell Science 115:4827-4841
( corresponding author)
31. Taupenot L, Harper KL, O'Connor DT (2003). Mechanisms of disease. The chromogranin-secretogranin family. N
Engl J Med 348:1134-1149
32. Lee J, Taylor CV, Gaucher SP, Toneff T, Taupenot L, Yasothornsrikul S, Mahata SK, Sei C, Parmer RJ, Neveu JM ,
Lane WS, Gibson B, O’Connor DT, Hook VY (2003). Identification of catestatin-containing intermediates and peptides
defines proteolytic cleavage sites utilized for converting chromogranin A to active, secreted catestatin of
neuroendocrine chromaffin cells. Biochemistry 42: 6938-6946
33. Greenwood TA, Cadman PE, Stridsberg M, Nguyen ST, Taupenot L, Schork NJ, and O'Connor DT. Genome-wide
linkage analysis of chromogranin B expression in the CEPH pedigrees: Implications for exocytotic
sympathochromaffin secretion in humans (2004). Physiol Genomics 18:119-127
34. Zhang L, Rao F, Wessel J, Kennedy BP, Rana BK, Taupenot L, Lillie E, Cockburn M, Schork NJ, Ziegler MG, and
O’Connor DT (2004). Functional allelic heterogeneity and pleiotropy of a repeat polymorphism in tyrosine hydroxylase:
prediction of catecholamines and response to stress in twins. Physiol Genomics 19:277-91
35. Taupenot L , Harper KL, and O’Connor DT (2005). Role of H + -ATPase-mediated acidification in sorting and release of
the regulated secretory protein chromogranin A: Evidence for a vesiculogenic function. J Biol Chem. 280: 3885–
3897. ( corresponding author)
36. O’Connor DT, Cadman PE, Smiley C, Salem R, Rao F, Smith J, Funk, SD, Mahata SK, Mahata M, Wen G, Taupenot
L, Gonzalez-Yanes C, Harper KL, Henry RR, and Sanchez-Margalet V (2005). Pancreastatin: Multiple actions on
human intermediary metabolism in vivo, variation in disease, and naturally occuring functional genetic polymorphism.
J Clin Endocrinol Metab 90:5414-5425
37. Greenwood TA, Rao F, Stridsberg M, Mahapatra NR, Mahata M, Lillie EO, Mahata SK, Taupenot L, Schork NJ,
O'Connor DT (2006). Pleiotropic effects of novel trans-acting loci influencing human sympathochromaffin secretion.
Physiol Genomics 25(3):470-9
38. Zhang K, Rao F, Wen G, Salem RM, Vaingankar S, Mahata M, Mahapatra NR, Lillie EO, Cadman PE, Friese RS,
Hamilton BA, Hook VY, Mahata SK, Taupenot L , and O’Connor DT (2006). Catecholamine storage vesicles and the
metabolic syndrome: The role of the chromogranin A fragment pancreastatin. Diabetes Obes Metab. 8:621-633. ( cocorresponding
author)
39. Courel M, Rodemer C, Nguyen ST, Pance A, Jackson AP, O’Connor DT and Taupenot L (2006). Secretory granule
biogenesis in sympathoadrenal cells: identification of a granulogenic determinant in the secretory prohormone
chromogranin A. J Biol Chem. 281:38038-38051
42. Ezzat E, Asa SL, Taupenot L, O'Connor DT, Lamberts SJ, Oberg KE (2006). Use of Tumor Markers in Neoplasms of
the Dispersed Neuroendocrine System. National Academy of Clinical Biochemistry laboratory Medicine Practice
Guidelines. Neuroendocrine tumors N3.
41. Rao F, Friese R, Wen G, Zhang L, Yuqing Chen, Das M, Zhang K, Hamilton BA, Schork NJ, Taupenot L, Mahata SK,
Ziegler MG, O’Connor DT (2006). Catecholamines, pheochromocytoma, and hypertension: genomic insights.
Comprehensive Hypertension. Gregory YH Hipp & John E. Hall , Editors; Mosby Elsevier, Publisher. p 8895-911

42. Inomoto C, Umemura S, Egashira N, Minematsu T, Takekoshi S, Itoh Y, Itoh J, Taupenot L, O'Connor DT, and
Osamura R (2007). Granulogenesis in non-neuroendocrine COS-7 Cell induced by EGFP-tagged chromogranin A
gene transfection: identical and distinct distribution of CgA and EGFP. J Histochem Cytochem 55:487-93
43. Arthur D, Taupenot L, and Insel P (2007). Nerve growth factor-stimulated neuronal differentiation induces changes in
P2 receptor expression and nucleotide-stimulated catecholamine release. J Neurochem. 100:1257-1264
44. O’Connor DT, Mahata SK, Mahata M, Jiang Q, Hook VY and Taupenot L (2007). Primary culture of bovine chromaffin
cells. Nature Protocols. 2: 1248-1253.
45. Lillie EO, Mahata M, Khandrika S, Rao F, Bundey RA, Wen G, Chen Y, Taupenot L, Smith DW, Mahata SK, Ziegler
MG, Cockburn M, Schork NJ, and O'Connor DT (2007). Heredity of endothelin secretion. human twin studies reveal
the influence of polymorphism at the chromogranin a locus, a novel determinant of endothelial function. Circulation
115:2282-91
46. Connolly R, Gates D, Loh N, Baban D, Thakker R, Johnston B, Mc Cance D, Ardill J, O’Connor DT, Taupenot L and
McGinty A (2007). Cox-2 promotes chromogranin A expression and bioactivity: Evidence for a PGE2-Dependent
mechanism and the involvement of a proximal cAMP-Responsive Element. Endocrinology 148:4310-7
47. Mosley CA*, Taupenot L* , Biswas N*, Taulane JP, Vaingankar SM, Wen G, Schork NJ, Ziegler MG, Mahata SK and
O’Connor DT (2007). Biogenesis of the secretory granule: chromogranin A (CHGA) coiled-coil structure results in
unusual physical properties and suggests a mechanism for granule core condensation. Biochemistry 46 :10999-
1012 (*equal contribution, co-corresponding author)
48. Taupenot L. Analysis of regulated secretion using PC12 cells (2007). Current Protocols in Cell Biology. Wiley
Interscience. Unit 15.12.
49. Rao F, Zhang L, Wessel J, Zhang K, Wen G, Kennedy BP, Rana BK, Das M, Rodriguez-Flores JL, Smith DW,
Cadman PE, Salem RM, Mahata SK, Schork NJ, Taupenot L , Ziegler MG , O'Connor DT (2007). Tyrosine
hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis. Discovery of common human genetic variants
governing transcription, autonomic activity, and blood pressure in vivo. Circulation 116:993-1006. ( co-corresponding
author)
50. Biswas N, Vaingankar SM, Mahata M, Das M, Gayen JR, Taupenot L, Torpey JW, O'Connor DT, and Mahata SK
(2007) Proteolytic cleavage of human chromogranin a containing naturally occurring catestatin variants: differential
processing at catestatin region by plasmin. Endocrinology 149:749-757
51. Radek K, Lopez-Garcia B, Hupe M, Elias PM, Niesman I, Taupenot L, Mahata SK, O’Connor DT, and Gallo R (2008).
The neuroendocrine peptide catestatin is a cutaneous antimicrobial and induced in the skin after injury. J Invest
Dermatol 128:1525-34
52. Courel M, Vasquez MS, Hook VY, Mahata SK, and Taupenot L (2008). Sorting of the neuroendocrine secretory
protein secretogranin II into the regulated secretory pathway: role of amino- and carboxy-terminal alpha-helical
domains . J Biol Chem 283:11807-22
53. Mahapatra NR*, Taupenot L* , Courel M, Mahata SK , and O’Connor DT (2008). The trans-Golgi proteins SCLIP and
SCG10 interact with chromogranin A to control exocytotic secretion from the regulated secretory pathway in
chromaffin cells. Biochemistry, Epub ahead of print (*equal contribution, co-corresponding author)
54. O’Connor DT*, Zhu G*, Rao F*, Taupenot L*, Das M , Mahata SK, Mahata M, Greenwood TA, Stridsberg M, Martin
NG, and Whitfield JB (2008). Heritability and genome-wide linkage in US and australian twins identifies novel genomic
regions controlling chromogranin A (CHGA): implications for secretion and blood pressure. Circulation. in press
(*equal contribution)
C. Research Support
Active:
NIH 2P01HL058120 (O’Connor/ Taupenot-Project 4) 06/15/2005–05/31/2010
“Sympathetic Neuroeffector Junctions and Blood Pressure”
Role: PI of a research project. “Trafficking of Catecholamine Storage Vesicle Proteins”
Major goal: Define mechanisms that modulate intracellular trafficking of catecholamine storage vesicle proteins.
American Heart Association Grant-in-Aid 0855181F (Taupenot, L), 07/01/2008-06/30/2010
Regulation of catecholamine storage and by the prohormone secretogranin II
Role: PI
Major goals: to understand the mechanisms by which SgII is sorted into the regulated secretory pathway and mediates
the formation of CSVs
Completed
NIH 2K01 DK59628 (Taupenot, Laurent) 06/01/2004 - 05/31/2006. No cost extension (06/01/2006-05/31/2007)
“Traffic of catecholamine storage vesicle proteins”
Role: PI
Major goal: Define intracellular mechanisms whereby the regulated secretory protein chromogranin A is sorted to
catecholamine storage vesicles in sympathoadrenal chromaffin cells.
NIH 1R01 DK067969 (Taupenot, Laurent) 08/15/2005 – relinquished, in compliance with NIH policy on concurrent
R01 and P01 awards.

Trafficking of Catecholamine Storage Vesicle Proteins
Role: PI.
Major goals: Define mechanisms that modulate intracellular trafficking of catecholamine storage vesicle proteins
NIH 1K01 DK59628 (Taupenot, Laurent) 06/01/01-05/31/04
Stimulus-event coupling in chromaffin secretory granules.
Role: PI.
Major goal: to understand secretory granule events in response to secretory stimuli in chromaffin cells.