BMP2K interacts with IRS2 and contributes to IRS2-dependent invasion. (A) MDA-MB-231 cells expressing IRS2-3×Flag-6×His were stimulated with IGF-1 (50 ng/ml) for 10 min. Cell extracts were immunoprecipitated with BMP2K-specific antibodies and immunoblotted with antibodies specific for either IRS2 or BMP2K. The data shown in the graph represent the means and SEM of the results of three independent experiments. Light, short exposure; dark, long exposure. (B) shRNAs targeting Bmp2k (shBmp2k#1 and shBmp2k#2) were expressed in PyMT:Irs1/2−/− cells expressing IRS2. Whole-cell extracts were immunoblotted with antibodies specific for Bmp2k, IRS2, and tubulin. (C) Matrigel Transwell invasion assay. The data shown represent the means and SEM of the results of three independent experiments. (D) Cells were stimulated with IGF-1 (50 ng/ml) for 10 min, and whole-cell extracts were immunoblotted with antibodies specific for IRS2, Bmp2k, pAkt (S473), Akt, and tubulin. The graph below represents the means and SEM of the results of three independent experiments. **, P < 0.01 relative to EV; #, P < 0.05 relative to IRS2-shGFP; ##, P < 0.01 relative to IRS2-shGFP. Molecular weight markers (in kilodaltons) are indicated to the left of the immunoblots.