TGFB1 and breast cancer: In light of the observation that Smurf2 targets the TGFβ receptors for ubiquitin-mediated degradation to suppress TGFβ signaling and biological effects [19, 20], our findings raised the question of whether the E3 ubiquitin ligase activity is required for the ability of Smurf2 to suppress TGFβ-induced invasive growth of breast cancer-derived organoids.