MAPK8 and ovarian cancer: As Ser245 of Smad2 is reported to be specifically phosphorylated by ERK and JNK in vascular endothelial cells and involved in endothelial dysfunction,41 our data expansively demonstrate that the phosphorylation sites of Ser245, Ser250 and Ser255 on Smad2 is involved in the ERK‐induced cascades at least in ovarian cancer cells with AGO1 knockdown.