Ubiquitination (via SCF-FBXW7, RNF20, RNF139) or deacetylation (via SIRT1) promotes SREBP1 degradation, inhibiting fatty acid metabolism and maintaining lipid homeostasis. mTORC1 activation and SREBP1 acetylation enhance its stability and promote lipid metabolism, supporting tumor growth. The gene discussed is FBXW7; the disease is neoplasm.