Angiopoietin-2 (Ang-2) is a secreted glycoprotein that plays a complex role in vascular development. Ang-2 contains an N-terminal coiled-coildomain, 58 - 254 amino acids (aa) and a C-terminal fibrinogen-like domain, 281 - 467 aa, that is also found in other proteins including fibrinogen, tenascin, and ficolin. Located at the N-terminus are stretches of hydrophobic residues typical of secretory signal sequences. While Ang-2 is widely expressed in the mouse embryo, it is restricted postnatally to pro-angiogenic regions including the placenta, ovaries, and uterus.

Ang-2 has been implicated in cancer development due to its role in angiogenesis.Ang-2-mediated destabilization of mature vessel structures accompanied by the presence of VEGF, may contribute to the angiogenesis associated with tumor tissues.