PPA2 and neoplasm: SETD7/9 methylates HIF1α, promoting its degradation, whereas the demethylase activity of LSD1 enhances HIF1α stability and contributes to tumor angiogenesis [58,59] PPA2 recruits the E3 ligase NEDD4 to degrade HIF-1α, while PPA2 desuccinylation inhibits NEDD4 activation, promoting HIF-1α stability and glycolysis [60].