SREBP-1 (E9F4O) Rabbit mAb #95879

Sterol regulatory element–binding proteins (SREBPs) are basic helix-loop-helix–leucine zipper (bHLH-Zip) transcription factors. Inactive precursor forms of SREBPs are bound to endoplasmic reticulum (ER) membranes. When cells are starved for sterols, SREBPs move from the ER to the Golgi apparatus with the help of SREBP cleavage activating protein (SCAP). In the Golgi apparatus, precursor SREBPs are then sequentially cleaved by two proteases, site-1 protease (S1P) and site-2 protease (S2P). The released N-terminal domain that contains the bHLH-Zip region enters the nucleus and binds to sterol response elements (SREs) in the promoters of a variety of genes responsible for the synthesis of cholesterol, fatty acids, and other lipids, activating their expressions (1,2). Studies show that SREBP-1-dependent fatty acid homeostasis has a critical role in promoting the pro-tumor phenotype of M2-like tumor-associated macrophages (TAMs), and inhibition of SREBP-1 enhances the efficacy of immune checkpoint blockade (3). In addition, suppression of cholesterol biosynthesis by statins stimulates SREBP-1 activation and, therefore, induces TGF-β signaling, promoting the epithelial-to-mesenchymal transition in pancreatic ductal adenocarcinoma (4).