Here, we provide several lines of evidence to suggest that PP1, IRS‐1/2, and pRb (p105) are involved in the TGF‐β‐stimulated TβR‐V‐mediated tumor suppressor signaling cascade (TβR‐V/IRS‐2/PP1/pRb). The gene discussed is TGFB1; the disease is neoplasm.