Figure 5. AP-1 is involved in S1P-facilitated PDGF-A expression and angiogenesis. (A) Cells were pretreated for 30 min with tanshinone IIA (3 μM), or transfected with c-Jun siRNA, then stimulated with S1P (10 μM). PDGF-A expression was examined by qPCR assays (n=5). (B, C) The CM was applied to EPCs and analyses assessed migratory and tube formation activity (n=4). (D) JJ012 cells were incubated with S1P (10 μM); c-Jun phosphorylation was examined by Western blot assay (n=3). (E) JJ012 cells were pretreated with manumycin A, GW5074, PD98059 and U0126 for 30 min, then stimulated with S1P (10 μM). The c-Jun phosphorylation was examined (n=3). (F, G) JJ012 cells were pretreated with Ras, Raf, MEK and ERK inhibitors or siRNAs, then stimulated with S1P (10 μM) and AP-1 Luciferase activity was examined (n=4). Results are expressed as the mean ± SEM. *p < 0.05 as compared with the control group; #p < 0.05 as compared with the S1P-treated group.