YY1 and pulmonary arterial hypertension: Although EZH2 was found to interact with YY1 (a known binding partner of EZH2) as expected [25], no interaction between EZH2 and E2F1 was detected (Figure S4C), adding further evidence that physical interaction between EZH2 and E2F1 is not required for EZH2 to promote E2F1 signaling in PAH-PASMCs.