Cancer induces Ptges in endothelial cells via ERK phosphorylation. (A) ERK1/2 was phosphorylated only in WT endothelial cells exposed to M27 cancer cells. (B) Inhibition of ERK1/2 with PD98059 decreased cancer-induced Ptges mRNA expression in WT endothelial cells. (C) PD98059 tended to inhibit Ptges protein expression in WT endothelial cells. (D) PGE₂ levels were reduced in the media of WT cultured with M27 cancer cells in the presence of PD98059. *P < .05 comparing WT vs WT + M27; **P < .05 comparing WT + M27 vs Gas6^−/− + M27; ***P < .05 comparing WT + M27 and WT + PD98059 + M27.