Figure 6

Src kinase is required for Wnt1-mediated extracellular signal-regulated kinase 1/2 (ERK1/2) activation. (a) c-Src was immunoprecipitated from lysates of Wnt1-expressing or vector control-expressing SkBr3 cells. The immunoprecipates were analyzed by SDS-PAGE/immunoblotting for p-Src and Src, and the signals were quantified versus control levels using the ImageQuant program. (b) T47D cells were pre-treated with the Src kinase inhibitor CGP77675 (2 μM) or dimethyl sulfoxide (DMSO) for 1 hour before treatment for 20 minutes with Wnt1 conditioned medium (CM). T47D/Wnt1 and SkBr3/Wnt1 cells were treated for 1 hour with CGP77675 or DMSO. Total lysates were analyzed by SDS-PAGE/immunoblotting for p-ERK1/2 and ERK1/2. (c) Src^-/- mouse embryonic fibroblasts transfected with a control plasmid or a wild type Src-expressing vector were treated with Wnt1 CM or control CM for 20 minutes. Total lysates were analyzed by SDS-PAGE/immunoblotting for p-ERK1/2 and ERK1/2. A representative result of three independent experiments is shown. EGF, epidermal growth factor; IP, immunoprecipitation; WB, Western blotting.