Fig. 5. Changes of ET-1, ERA, eNOS, and MMP-2 protein expression levels after hUCB-MSCs injection in PAH rats. These are pictures of protein expression levels of ET-1, ERA, eNOS, and MMP-2 in the lung tissues. The protein expression levels of ET-1, ERA, eNOS, and MMP-2 were significantly increased in the M group compared with the C group at weeks 2 and 4. The protein expression levels of ET-1, ERA, eNOS and MMP-2 were significantly decreased at week 4. ^*P < 0.05 compared with the C group, ^†P < 0.05 compared with the M group. C, control group; M, monocrotaline group; U, hUCB-MSCs group.