STAT5A and pulmonary arterial hypertension: In as much as it is known that BCL6 is a broad-spectrum transcriptional repressor [49–52], the reduced expression of BCL6 in SMC:STAT5a/b−/− mice prompted us to test the involvement of BCL6 per se in the sex bias observed in this model of PAH by genetically deleting BCL6 in SMCs in mice.