Abstract: The present invention provides methods for modulating pluripotency of stem cells and proliferation of cancer cells. The modulation is achieved by promoting dephosphorylation of mRNA-binding protein 3 (RBM3) and down-regulating expression or cellular level of pluripotency factor LIN28. Related methods are provided in the invention for promoting differentiation of stem cells and for inhibiting growth of tumors in subjects. The therapeutic methods of the invention typically entail contacting with a target cell (e.g., a tumor cell) or administering to a subject harboring the target cell a calpain inhibitor and/or an IGF1R inhibitor. Some methods of the invention employ both a calpain inhibitor and an IGF 1R inhibitor.