TGFB1 and pulmonary arterial hypertension: A previous study showed that PAH rats injected with TGF-β1 recombinant protein could activate the mRNA and protein expression of RhoA and ROCK, revealing that overexpression of TGF-β1 might activate the RhoA/ROCK signaling pathway and promote the occurrence and development of PAH (Fig. 2) [56].