TGFB1 and cancer: TGF-β1 binds to two cognate serine–threonine kinase receptors on the cancer cell surface; the type I receptor TβRII transphosphorylates the type I receptor TβRI, leading to the phosphorylation of R-Smads that form complexes with co-Smads in the nucleus, and these complexes bind DNA to regulate EMT target genes via cooperative interactions with Slug, Snail, and other transcription factors [14].