ide , ▁par ath y roid ▁h orm one - related ▁protein ▁( P TH r P ), ▁alpha - human ▁ch or ionic ▁g on ad otrop in ▁( h CG ), ▁som at ost atin , ▁ch ole c yst ok in in , ▁v aso active ▁int est inal ▁pe pt ide ▁( V IP ), ▁ne urope pt ide ▁Y , ▁v asc ular ▁end oth el ial ▁growth ▁factor ▁( V EG F ), ▁and ▁ad ren omed ull in . ▁The ▁phys i ology ▁of ▁their ▁secret ion ▁and ▁its ▁reg ulation ▁is ▁in comple t ely ▁understood . ▁Reg ul atory ▁c ues ▁might ▁come ▁through ▁end ocr ine , ▁par ac r ine ▁( from ▁neighbor ing ▁ne uro end ocr ine ▁cells ), ▁aut ocr ine ▁or ▁ne uro cr ine ▁routes . ▁The ▁open ▁type ▁cells ▁may ▁in ▁addition ▁receive ▁regul atory ▁signals ▁from ▁lum inal ▁mole cules ▁The ▁development al ▁origin ▁of ▁these ▁cells ▁is ▁as ▁yet ▁unknown . ▁They ▁are ▁thought ▁to ▁arise ▁from ▁a ▁different ▁prec ursor ▁than ▁other ▁ep ith el ial ▁pro static ▁cells , ▁possibly ▁through ▁a ▁ne uro gen ic ▁line age ▁of ▁their ▁own , ▁which ▁is ▁therefore ▁distinct ▁from ▁the ▁secret ory ▁and ▁bas al ▁cells ▁that ▁derive ▁from ▁u ro gen ital ▁sin us . ▁ ▁Ro le ▁in ▁pro state ▁cancer ▁The ▁most ▁heavily ▁studied ▁aspect ▁of ▁ne uro end ocr ine ▁different iation ▁in ▁pro state ▁cancer ▁( but ▁not ▁the