The protein encoded by this gene is localized in the endoplasmic reticulum (ER) and golgi, and is also secreted. Reducing expression of this gene increases susceptibility to ER stress-induced death and promotes cell proliferation. The protein was initially thought to be longer at the N-terminus and to contain an arginine-rich region but transcribed evidence indicates a smaller open reading frame that does not encode the arginine tract. The presence of a specific mutation changing the previously numbered codon 50 from ATG to AGG, or deletion of that codon, has been reported in a variety of solid tumors. With the protein size correction, this codon is now identified as the initiation codon. [provided by RefSeq]