SMAD3 and cancer: Several reports showed that RBP2 stimulated various processes such as HIF-1α–VEGF-induced angiogenesis in non-small cell lung cancer through the Akt pathway51, malignant progression of GA through the TGF-β1-(p-Smad3)-RBP2-E-cadherin-Smad3 feedback circuit52, induction of stem-like cancer cells by promoting epithelial-mesenchymal transition in renal cell carcinoma53, and initiation of ER and IGF1R-ErbB signaling in tamoxifen resistance in breast cancer54.