IRS1 and neoplasm: We previously demonstrated that IGFBP‐3 and TGF‐β inhibit growth in epithelial cells by stimulating TβR‐V‐mediated tumor suppressor signaling which involves IRS‐1/2‐dependent activation and cytoplasm‐to‐nucleus translocation of IGFBP‐3‐ or TGF‐β‐stimulated protein phosphatase (PPase), and dephosphorylation of retinoblastoma family proteins in the nucleus, resulting in cell growth arrest.7, 10, 22, 23