Ectonucleotide pyrophosphatase/phosphodiesterase 3 (ENPP3/CD203c/PD-beta) is a type-II transmembrane glycoprotein that contains a large extracellular domain, an alpha-helical transmembrane segment, and a short cytoplasmic domain containing the N-terminus. ENPP3 has been shown to be overexpressed in colon carcinoma and is thought to play a role in tumor initiation and tumor cell invasiveness. Within the hematopoietic cell compartment, ENPP3 is a cell surface marker of basophil and mast cell lineages. Indeed, ENPP3 is overexpressed on transformed mast cells in patients with systemic mastocytosis. Recently, ENPP3 has been identified as being highly overexpressed in renal cell carcinoma (RCC) and may have potential as a novel therapeutic target for this disease.
