The EP4 inhibitor AH23848 blocks the L-902,688-induced suppression of TGF-β-induced EndMT in HUVEC. TGF-β-induced expression of the EndMT markers α-SMA and Twist in endothelial cells was suppressed by L-902,688. The endothelial cells were stimulated for 30 min with 100 µM AH23848 with or without L-902,688 or TGF-β for 24 h. Data are the mean ± SE of three different experiments. * p < 0.05, ** p <0.01, and *** p < 0.001 versus untreated group. (A) Representative immunoblots showing that the suppression of TGF-β-induced expression of α-SMA and Twist by 1 µM L-902,688 was reversed with an EP4 inhibitor (AH23848) at 100 µM. (B) Densitometry quantification of α-SMA and Twist expression following EP4 inhibitor treatment in endothelial cells.