VEGFA and neoplasm: In fact, it was observed that cooption of pre‐existing vasculature by tumor cells leads to upregulation of angiopoietin‐2 (Ang‐2) expression in co‐opted endothelial cells, which causes apoptosis in endothelial cells, vascular regression, and collapse in the absence of VEGF.[110] Tumor cells in immediate proximity of degenerated vessels begin to die, forming initial foci of necrosis.