Prokineticin 2 is known to regulate many different biological functions, including neurogenesis, smooth muscle contractility, angiogenesis and circadian rhythm. In serving the latter role, prokineticin 2 functions as an output molecule from the suprachiasmatic nucleus (SCN) of the hypothalamus, that transmits behavioral rhythms, but may also function locally within the SCN to synchronize output. Prokineticin 2 expression is induced by CLOCK and BMAL1 heterodimers and light, and is inhibited by period genes (PER1, PER2 and PER3) and cryptochrome genes (CRY1 and CRY2). Expression is reported in the SCN and among a few other discrete brain areas, including the islands of Calleja, media l preoptic area of the hypothalamus and the shell of the nucleus accumbens as well as in the testis, prostate and, at lower levels, in the small intestine.