MMP9 and prostate cancer: Dkk-3, a secreted protein, inhibits TGF-β-induced expression of matrix metallopeptidase 9 (MMP9) and MMP13 to prevent migration and invasion of prostate cancer.344 Cancer upregulated gene 2 promotes cellular transformation and stemness, which is mediated by nuclear NPM1 protein and TGF-β signaling in lung cancer.345 TGF/Smad also plays an important role in the cell proliferation of CSCs.