PAFAH2 and pulmonary arterial hypertension: Importantly, PAF-AH2 is abundantly expressed in mast cells and contributes to constitutive (i.e., stimulus-independent) generation of unique epoxy-metabolites of ω3 fatty acids (ω3 epoxides), which prime mast cells to ensure optimal FcεRI-dependent activation (Figure 4A) and attenuates pulmonary hypertension by reducing the expression of pro-fibrotic factors (Figure 4B) in autocrine and paracrine manners, respectively (18, 19).