Furthermore, histone methylation has recently also been implicated in PAH, more specifically in hypoxia-induced PAH, where megakaryocytic leukemia 1 (MKL1) is upregulated and leads to an increase in the recruitment of the H3K4-specific complex components, ASH2 and WDR5 [130,131]. Here, WDR5 is linked to pulmonary arterial hypertension.