DPP4 and hepatocellular carcinoma: Similarly, hydroxymethylglutaryl-CoA lyase (HMGCL) influences histone H3 lysine 9 (H3K9) acetylation via β-hydroxybutyrate, which regulates dipeptidyl peptidase 4 (DPP4) expression in a dose-dependent manner, promoting ferroptosis in HCC cells [50].