EPCAM and retinoblastoma: Recently, Krishnakumar et al. have shown that epithelial cell adhesion molecule (EpCAM) is highly expressed in RB tumors with invasion compared to tumors without invasion.72 EpCAM, also known as ESA or EGP40, is a 40-kDa epithelial transmembrane glycoprotein that is encoded by the GA733-2 gene located on the long arm of chromosome 4.