In this study, we sought to study whether CALHM1 and/or CALHM2 were involved in PASMC phenotypical transition from the contractile or differentiated phenotype to the synthetic or proliferative phenotype, and whether CALHM1/2 are upregulated in PASMCs from patients with PAH and animals with experimental PH in comparison to respective controls. Here, CALHM2 is linked to pulmonary arterial hypertension.