Masri et al investigated differences in Bcl-2 and Mcl-1 protein levels in idiopathic pulmonary arterial hypertension (IPAH) pulmonary artery endothelial cells (PAEC) vs control PAEC and there is little to no expression of these proteins in control PAECs [38]. Here, MCL1 is linked to idiopathic pulmonary arterial hypertension.