CUB domain containing protein 1 (CDCP1, SIMA135) is a putative stem cell marker shown in research studies to be highly expressed in some human cancer cells and in both typical and atypical (cancerous) colons. Expression of CDCP1 may be epigenetically regulated, as methylation of promoter CpG sequences results in decreased CDCP1 expression. The corresponding CDCP1 gene encodes a glycoprotein that acts as a complex, multidomain transmembrane antigen. CDCP1 has three extracellular CUB domains that may be involved in cell adhesion or extracellular matrix interactions. Src-family kinases may phosphorylate CDCP1 at five tyrosine residues within its cytoplasmic domain to provide a potential binding site for SH2 domain-containing proteins. CDCP1 is a putative hematopoietic stem cell marker.
