MiR-31 is a major regulator of Wnt, BMP, and TGF-β signaling, controlling intestinal stem cell proliferation, intestinal homeostasis, and colorectal cancer progression by binding the 3′-UTR of ERK5, RAS1, TGF-β, β-catenin, and several other mRNAs to control cell migration, cell proliferation in vitro, and tumorigenesis and metastasis in vivo [61]. The gene discussed is TGFB1; the disease is colorectal cancer.