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. Author manuscript; available in PMC: 2015 Jan 1.
Published in final edited form as: Cell Signal. 2013 Sep 12;26(1):10.1016/j.cellsig.2013.08.043. doi: 10.1016/j.cellsig.2013.08.043

Fig. 4.

Fig. 4

HER2 kinase activity is required for MTK1/HER3 association. MCF-7 cells were pre-treated with 0, 50, 100 or 200 nM lapatinib for 1 h followed by 10 nM HRG stimulation for 12 min. Phosphotyrosine immunoblot analysis of MTK1 immunoprecipitations show 50 nM lapatinib attenuates MTK1/HER3 association (Panel A, lane c). Cell extracts (150 μg) that were used for the immunoprecipitation were resolved by SDS-PAGE and immunoblotted for phosphotyrosine (B, top panel). HER2 negative, but HER3 positive MDA-MB-231 cells were stimulated with 10 nM HRG followed by MTK1 immunoprecipitations and compared to T-47D and MCF-7 cells. Phosphotyrosine immunoblot analysis shows HER2 is required for MTK1/HER3 association in response to HRG (Panel C, lane c). Membranes were stripped and immunoblotted for MTK1 (A, B and C, bottom panels).