SMAD2 and cancer: Specifically, researchers found that these miRNAs inactivated the TGF- β signaling pathway (an oncogenic pathway in later cancer stages) via targeting several important factors, including SMAD2, SMAD4, and TGFBR1 (for miR-582-3p); and SMAD2, TGFBR1, as well as TGFBR2 (for miR-582-5p).