KLF5 expression is increased in PAH. A) KLF5 expression is measured by qRT-PCR in human lungs from patients with or without PAH. KLF5 is increased in PAH-patient (n = 10) compared to control patients (n = 8). KLF5 expression is also increased in distal pulmonary arteries (PA) of MCT-PAH-rats versus control rats (n = 10). B) KLF5 upregulation (measured by qRT-PCR) is correlated with PAH severity in human lung evaluated by pulmonary vascular resistance (PVR). Similarly, KLF5 expression in rat lungs is correlated with mean PA pressure upregulation. C) KLF5 upregulation (measured by (1) qRT-PCR or (2) Western blot) is confirmed in human pulmonary artery smooth muscle cell (PASMC) isolated from healthy patients or PAH patients (3&4). All qRT-PCR results were normalized to 18S gene expression and protein expression was measured by Western blot were normalized to SM-actin (*, P < 0.05; **, P < 0.01).