Nectin-4/Poliovirus Receptor-Like 4 (PVRL4) is a type-I transmembrane glycoprotein that belongs to the immunoglobulin superfamily and promotes cell-cell adhesion by serving as a major component of adherens junctions. The extracellular domain of Nectin-4, which contains an Ig variable-like domain (V) and two Ig constant-like domains (C), mediates binding to the measles virus and to neighboring cells through trans heterophilic interactions with Nectin-1. Unlike other nectin family members, which are widely expressed in adult tissues, Nectin-4 expression in humans is largely restricted to the placenta. Research studies have demostrated that Nectin-4 is overexpressed in a variety of human solid tumors of the pancreas, breast, lung, and ovary. Due to its restricted expression pattern in normal human tissues, Nectin-4 may serve as a novel diagnostic and therapeutic target for a variety of human tumors.
