FASN is a multifunctional protein whose primary function is to catalyze the synthesis of palmitate from acetyl-CoA and malonyl-CoA into long-chain saturated fatty acids. In some cancer cell lines, this protein has been found to be fused with estrogen receptor-alpha (ER-alpha), in which the N-terminus of FAS is fused in-frame with the C-terminus of ER-alpha. Wild-type FASN has been found to be overexpressed in a number of cancers, and is thought to contribute to tumor cell growth and survival. FASN is also implicated in the progression of diabetes and liver disorders, and inhibitors of FASN are of interest in the treatment of these diseases as well as cancer. In immunohistochemistry of normal tissue, FASN has cytoplasmic positivity in glandular cells and adipocytes in the breast, it is present in the brain, lung, and liver, and is also found at lower levels in most other tissues throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804; ACS Med Chem Lett. 2015 Aug 13; 6(8): 838–839, PMID: 26288680; Nat Rev Cancer 7, 763–777 (2007), DOI:10.1038/nrc2222;