HIF1A and neoplasm: In order to meet the lipid demand of rapid proliferation, the enzymes related to de novo lipid synthesis in tumor cells are abnormally highly expressed, such as fatty acid synthase (FASN) which catalyzes the synthesis of palmitic acid by acetyl-CoA and malonyl-CoA.306,307 One of the possible mechanisms of upregulated FASN under hypoxia of TME is the activation of Akt-HIF-1 axis and the following induction of transcription factor SREBP-1.308 Multiple acetylation sites were identified on FASN.