Breast cancer-overexpressed gene 1 protein (KIAA0100) is a glucoprotein composed of 2,235 amino acids. KIAA0100 has four isforms (254kDa,250kDa,45kDa,25kDa).KIAA0100 is expressed in pancreas, placenta and up-regulated in breast carcinoma epithelial cells. This gene was initially characterized in human as having high expression levels in breast carcinomas and breast cancer cell lines. This gene also has increased expression in prostrate cancer cells relative to normal prostrate tissues. Expression of this gene is negatively regulated by direct binding of the microRNA miR-195 to its 3' UTR. miR-195 has been shown to modulate the invasiveness of prostrate cancer cells and xenograft metastases by downgrading expression of this gene. In mouse, the protein encoded by this gene was identified as an antigen on acute monocytic leukemia cells. In human, alternative splicing results in multiple transcript variants encoding distinct isoforms; some of these isoforms are predicted to contain an RNA pol II promoter FMP27 protein domain and a Golgi-body-localization APT1 domain.