Matrigel-induced network formation of trophoblast 3A cells was inhibited by SERPINE2 antiserum or siRNA. (A) Treatment of 3A cells with SERPINE2 antiserum or siRNA significantly blocked the formation of the capillary-like network, as scored by the number of branch points and total length formed following 24 h of treatment. (B) SERPINE2 mRNA levels in 3A cells in Matrigel compared to controls. (C) Western blot analysis was used to detect the secreted SERPINE2 protein in the supernatant of 3A cells in the tube formation assay. Each experiment was carried out in triplicate, and each bar represents the mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001 compared to the scrambled siRNA-treated controls. Representative images of capillary-like network formation by 3A cells are shown. Scale bars represent 100 μm.