HDAC2 and pulmonary arterial hypertension: Notably, RNA interference of HDAC1 (Lane C-B), HDAC2 (Lane D-B), and HDAC8 (Lane E-B) isoforms in PAH-PAAFs, specifically modulated transcription of a subset of genes (Fig. 4D) and signaling pathways (Fig. 4E), in comparison to the scrambled siRNA treated (controls) IPAH-PAAFs.