TGFB1 and neoplasm: The answer shows how opportunistic the tumor cell can be: colon cancer cells with a disabled TGF-β1 pathway but un-impaired synthesis of the cytokine exploit the “wild type” TGF-β1/SMAD signaling pathway fully operative in CAFs to elicit pro-tumorigenic signals which, in turn, impinge back on them, providing a vicious loop that ultimately sustains their relentless oncogenic agenda (Figure 1).