BRD3 and pulmonary arterial hypertension: In the RV, no increase in BRD2 and only a small increase in BRD3 were observed.11 Enhanced BRD4 expression was also induced during RV hypertrophy in a rat PAH model.12 BRD4 mRNA is expressed at 10 times the level of BRD2 and BRD3 in cardiomyocytes and prophylactic JQ1 treatment is effective at counteracting the effect of two different inducers of left ventricular heart failure particularly in relation to the inflammatory drive.28 This provides an excellent rationale for the extension into therapeutic interventions in a mouse model of PAH.