Angiopoeitin-2 (Ang-2) is a multimeric ligand involved in the angiopoietin-Tie signaling system that binds the Tie2 receptor and is characterized as a modulator of endothelial permeability and barrier function. It is predominantly expressed by endothelial cells and some smooth muscle cells, with increased expression in many inflammatory and angiogenic conditions, such as inflammation-induced vascular remodeling and tumor angiogenesis. Ang-2 expression has been documented in a range of human cancers, including glioblastoma, melanoma, prostate adenocarcinoma, and renal cell carcinoma.