COL18A1 and neoplasm: Endostatin is the 20 kDa C-terminal cleavage product of collagen XVIII that has been shown to have a number of anti-angiogenic properties including inhibition of endothelial cell proliferation [22] and migration [23,24], induction of endothelial cell apoptosis [25], and inhibition of tumor growth in vivo [22,26-28].