SIRT5 and cancer: Mitochondrial serine hydroxymethyltransferase 2(SHMT2) is a key enzyme in single-carbon unit metabolism that is significantly elevated in most cancer types.[49] It has been reported that SHMT2 can promote the proliferation of cancer cells by catalyzing the rate-limiting step of serine catabolism.[50] SIRT5 mediates the desuccinylation of Lys280 to SHMT2, activates the enzyme SHMT2, and promotes serine catabolism in tumor cells.[51]