TGFB1 and pulmonary arterial hypertension: Similar to the research of Gore et al., the ALK1 overexpression in studies, in the animal model of monocrotaline-induced pulmonary hypertension, was shown by Ramos et al. [15] However, a study conducted on a similar model by Zakrzewicz et al. showed a decrease in expression of the TGF-β pathway proteins [16].