May be involved in the regulation of cell proliferation. Has a cell-proliferation inhibition activity in vitro. May act as a modulator of nicotinic acetylcholine receptors (nAChRs) activity. In vitro inhibits nicotine-induced signaling probably implicating alpha-3:beta-2- or alpha-7-containing nAChRs. Interacts with CHRNA4. Highly expressed in prostate (basal, secretory and neuroendocrine epithelium cells). Also found in bladder (transitional epithelium), placenta (trophoblasts), stomach (neuroendocrine cells), colon (neuroendocrine cells) and kidney (collecting ducts). Overexpressed in prostate cancers and expression is correlated with tumor stage, grade and androgen-independence. Highly expressed in prostate cancer bone metastases. Expressed in gastric epithelial cells, mainly in the isthmus (at protein level). Not detected in normal intestinal epithelium (at protein level). Expressed in brain cortex; expression is significantly increased in the front cortex of Alzheimer disease patients. Down-regulated in gastric cancer cells. N-glycosylated. Genetic variations in PSCA may influence susceptibility to some cancers. A polymorphism gives rise to an upstream methionine which produces a longer protein of 123 residues associated with various cancers including diffuse-type gastric cancer and urinary bladder cancer. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus.