Interestingly, CDKN1A levels were decreased in a rodent model of PAH27 and JQ1 increased CDKN1A protein expression in PAH‐PASMCs within 16 h of treatment showing rapid arrest of proliferation by BRD4 inhibition.11 Previous studies have shown that JQ1 inhibited proliferation and differentiation of mouse cancers in vivo and of a number of other cell lines in vitro.17 This suggests a potential anti‐remodelling effect of JQ1+ by BRD4 inhibition in pulmonary microvascular endothelial cells. This evidence concerns the gene BRD4 and pulmonary arterial hypertension.