OCC-1 (Overexpressed in colon carcinoma-1) was initially identified as a novel human cDNA overexpressed in a colon carcinoma cell line.  Elevated levels of OCC-1 mRNA were observed in three of eight colon carcinomas, suggesting that OCC-1 may be a hallmark of only a subset of colon carcinomas.  It is highly expressed in skeletal muscle, kidney, placenta, and pancreas tissues, with low to no expression in heart, brain, lung and liver tissues.   At least two different OCC-1 mRNA species are known to exist.  In vitro transcription and translation of the OCC-1 cDNA yields polypeptides less than 9 kDa.  Despite this, OCC-1 from cell lines is detected at ~28 kDa in SDS-PAGE.