Figure 4.

IGF2BP1 promotes SRC activation via its SH3-binding VP₄SS motif. (A) Schematic representation of VP₄SS conservation among IGF2BP1 orthologs and human paxillin. The domain organization of IGF2BP1 wild type and mutants is shown in the upper panel (RRM, RNA recognition motif; KH, hnRNPK homology domain). Stars depict mutations of the GXXG loop inhibiting RNA binding [30]. (B) Representative Western blot analyses of indicated proteins in ES-2 cells transiently expressing GFP alone (lane 1) a mixture of GFP and indicated GFP-fused proteins (lane 2) or only GFP-fused proteins. WT, GFP-IGF2BP1_WT; ∆SH3, GFP-IGF2BP1_∆SH3; SH3motif, GFP-VP₄SS; KHmut, GFP-IGF2BP1_KHmut. VCL served as loading control. (C) Quantification of Western blots shown in (B). Error bars indicate SD determined in three independent experiments. Statistical significance was tested by Student’s T-test. *, p < 0.05; **, p < 0.01