Gastrotropin, also known as Fatty acid-binding protein 6, Ileal lipid-binding protein, ILBP, Intestinal 15 kDa protein, Intestinal bile acid-binding protein, I-BABP and FABP6, is a cytoplasm protein which belongs to thecalycin superfamily and Fatty-acid binding protein (FABP) family. Isoform2 of FABP6 is expressed in colorectal adenocarcinomas and their adjacent normal mucosa (at protein level). Isoform1of FABP6 is expressed in the jejunum, ileum, cecum and ascending colon intestine. Isoform2is expressed in the gallbladder, duodenum, jejunum, ileum, cecum, ascending, transverse and descending colon, sigmoid colon and rectum. FABP6 / I-BABP is a cancer-related protein that acts as an intracellular transporter of bile acid in the ileal epithelium. FABP6 / I-BABP may also play an important role in early carcinogenesis.