May be involved in the regulation of cell proliferation. 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. Predominantly expressed in prostate. Also found in spleen, liver, lung, prostate, kidney and testis. Expressed in brain cortex; expression is increased in transgenic mouse model of Alzheimer disease (at protein level).