TRAP1 and cancer: TRAP1 elevates the cellular concentration of succinate, leading to inhibition of PHD and subsequent stabilization of HIF1α, by inactivating succinate dehydrogenase (SDH) in cancer cells.[23] However, TRAP1‐HIF1α regulation in the retina does not involve SDH and PHD because it was unaffected by treatment with a large excess of succinate (Figure S14A, Supporting Information), the PHD inhibitor dimethyloxalylglycine (DMOG), and a HIF1α mutant (P402A and P564A) lacking PHD hydroxylation sites (Figure S14B, Supporting Information).