Based on our proposed model (Fig. S7), repeated exposure of epithelial cancer cells in oral tumors to TGF-β1 (that is, repeated switching between the EMT and MET mediated by fluctuations in the extracellular TGF-β1 concentration in tumors) might allow these cells to develop into aE cancer cells with potentially higher malignancy, akin to SAS-δ. This evidence concerns the gene TGFB1 and cancer.