GRB2 and neoplasm: Parallel to several studies which implicate crosstalk between estrogens and insulin/IGF-I signaling in breast carcinogenesis, tumor cell proliferation, differentiation and survival [33], [34], [35], [36], our observation implies that IRS1pY47 interaction with GRB2 might be through SH2BP2 [13], a key regulator of ER alpha and IGF-1R signaling crosstalk in promoting cell proliferation and survival critical in ER positive (MCF7 and T47D) tumor cells.