CD74 and pulmonary arterial hypertension: Among the candidates conserved across species, we focussed on CD74, as an increase in EC CD74 protein level has previously been identified in human PAH samples.45 CD74 is a receptor for the macrophage migration inhibitory factor, and the CD74/MIH complex was associated with PAH and linked to the recruitment of leucocytes to ECs in vitro.45 The scRNA-seq revealed that Cd74 up-regulation is associated with changes to MHC-II genes, suggesting that the CD74/MHC-II complex might contribute to PAH progression.