CCL2 and pulmonary arterial hypertension: The main cluster populated by the Oasl1−/−Apoe−/− mouse group (EC Sub-cluster 4) showed increased expression of genes associated with pulmonary hypertension and atherosclerosis, including Selp, Edn1, Ctla2a, Ccl2, Mmrn1, Plvap, and Lgmn (Fig. 4h, Supplementary Fig. 7b).