Fig. 5

a Quiescent cells were treated with different concentrations (0, 25, 50 or 100 μg/ml) of oxLDL for 10 min. Treatment was terminated by washing the cells with ice-cold PBS. Cells were lysed in 100 μl of lysis buffer containing protease and phosphatase inhibitor cocktails. Protein content in the samples was determined using the bicinchoninic acid assay, and the samples were heated at 100 °C in 5× protein loading dye for 5 min. Equal amounts of protein were separated by SDS-polyacrylamide gel electrophoresis, transferred to a polyvinylidene fluoride membrane and probed with monoclonal antibodies against total and phosphorylated SHP2 and ERK1/2. OxLDL activated SHP2 in a concentration-dependent manner. Total SHP2, phosphorylated SHP2, total ERK and phosphorylated ERK levels were examined by Western blot. Relative quantification of target proteins was performed by comparing band density levels among samples. The results are reported as the mean ± SE (n = 3 per group). *p < 0.05 vs. the no-oxLDL treatment group. b Effects of SHP2 on VSMC proliferation. Smooth muscle cells were exposed to different concentrations (0, 25, 50 or 100 μg/ml) of oxLDL for 24 h. BrdU (1 μmol/L) was added, and the cells were incubated for 3 h. BrdU incorporation was quantified using the BrdU cell proliferation assay kit. The percentage of BrdU-positive VSMCs was determined. Data are presented as the mean ± SE of three independent experiments. *p < 0.05 vs. the no-oxLDL treatment group