CUB domain-containing protein 1(CDCP1) is a transmembrane glycoprotein with a large extracellular domain (ECD) containing two CUB domains, and a smaller intracellular domain (ICD) containing five tyrosines. CDCP1 is widely expressed in human epithelial tissues, but its phosphorylation is only seen in mitotically detached or shedding cells, consistent with its role in the negative regulation of cell adhesion. The tyrosine phosphorylation of CDCP1 in cultured cells occurs when cells are induced to detach by trypsinor EDTA, or seen spontaneously during mitotic detachment. The overexpression of CDCP1 leads to the loss of cell adhesion and a detached phenotype.