TGF-β1 Gene structure. Exon 1 encodes the 5’UTR that contains the Promoter region 2, the signal peptide (SP), and part of the mature protein. The end of exon 5 to exon 6 encodes the mature TGF-β1, and the other exons encode the LAP. Upstream, the exon 1 is present in the Promoter region 1 (P1), Negative region 1 (N1), Enhancer region 1 (E1), Negative region 2 (N2), and Enhancer region 2 (E2). The functional polymorphisms are presented with their respective position and sequence.