E2F1 and pulmonary arterial hypertension: In support of this, we found that expression levels of well-established cell promoting factors and E2F1 targets genes, i.e., MCM2, RRM2, KPNA2, and PTTG1 [22], were diminished by EZH2 knockdown and further reduced in PAH-PASMCs simultaneously exposed to the pan-E2F inhibitor HLM006474 and siEZH2 (Figure S4B).