Association of Lyn and Src SH3 domains with hGMR-α. (A) Detection of hGMR-α and Lyn in whole-cell lysates (WCL) from HEK293T cells expressing hGMR-α, and 4H1 immunoprecipitates (4H1 IP) of the same cells. (B) Detection of hGMR-α and Lyn in WCL from HEK293T cells expressing hGMR-α or hGMR-α-APVA, and in 4H1 (4H1 IP) and control IgG1 (IgG₁) immunoprecipitates of the same cells. (C) Detection of hGMR-α and Src in WCL from HEK293T cells expressing hGMR-α or hGMR-α-APVA, and in 4H1 (4H1 IP) and control IgG1 (IgG₁) immunoprecipitates of the same cells. (D) Fluorescence polarization analysis of a fluorescein-conjugated mGMR-α peptide alone, with GST, or with p85, Lyn and Src SH3 domain GST fusions proteins. The change in millipolarization (Δmp) is given, where emissions of the mGMR-α peptide alone have been subtracted from the other samples. (E-F) FDB1 cells cultured in 500 BMU of mIL-3 and FDB1 cells expressing FIΔ or V449E cultured in the absence of growth factor were treated with DMSO, (E) 0.5μM SU6656 or 25μM PP1, or (F) 10μM and 25μM Lyn peptide inhibitor (LI) for 24 hours. Viability was measured by trypan blue exclusion. Error bars represent SEM, where n = 2; statistical significance was calculated by the use of a Student t test, *P < .05 **P < .01.