BMPR2 and heritable pulmonary arterial hypertension: In addition, estrogen influences B cell maturation andselection and may account for the differences observed in, EBV-immortalizedcells and in males and females.124 Furthermore, the BMPR2 ligands, BMP2 and BMP4, also have roles in thedevelopment, growth potential and apoptosis of B cells.125 As the B cells studied were from HPAH patients with dysfunctional BMPR2signalling, they may be phenotypically altered, resulting in changes to estrogenmetabolism and differential expression of CYP1B1 compared to human PASMCs fromHPAH patients.