The human protein tyrosine phosphatase beta often is abbreviated as ΗΡΤΡβ or HPTP beta, which removes the phosphate from the Tie-2 receptor. ΗΡΤΡβ plays a functional role in endothelial cell proliferation, viability, differentiation, vasculogenesis, and angiogenesis. ΗΡΤΡβ and vascular endothelial protein tyrosine phosphatase (VE-PTP; the mouse orthologue of ΗΡΤΡβ) are expressed in vascular endothelial cells throughout development.