Epithelial Cellular Adhesion Molecule (EpCAM), also known as TROP 1, is a calcium-dependent homophilic adhesion protein. It associates into tetramers and forms complexes in cis with Claudin-7, CD44v6, TSPAN8, CD9, Integrin alpha 3, and Annexin A1. During embryonic development, EpCAM is expressed in lung, kidney, liver, pancreas, skin, and germ cells. In the adult, it is expressed on basolateral cell membranes of simple, pseudo-stratified, and transitional epithelia. EpCAM is upregulated in proliferating epithelial tissues, during adult liver regeneration, and many carcinomas.