A. Mouse SSCs were incubated with 10 ng/ml B7-H3 for 0, 15, 30 and 60 min in vitro, and cell lysates were assessed by western blot using anti-phospho-PI3K, anti-phospho-ERK1/2 and anti-phospho-JNK1/2/3 antibodies. GAPDH was used as a loading control. B. to D. Graphs represent the quantification of phosphorylation of PI3K, ERK1/2 and JNK1/2/3 shown in (A), respectively, which was normalized to the corresponding GAPDH in three independent experiments. E. Mouse SSCs were incubated with different concentrations of B7-H3 (0, 5, 10, 25 ng/ml) for 30 min in vitro, and cell lysates were assessed by western blotting using an anti-phospho-PI3K antibody. PI3K was used as the loading control. F. The graph represents the quantification of phosphorylation of PI3K shown in (E), which was normalized to the corresponding PI3K in three independent experiments. The results are expressed as the mean±standard deviation (n = 3). Differences were analyzed by one-way ANOVA followed by Tukey's post hoc analysis. *P < 0.05, ***P < 0.001, ****P < 0.0001.