COL4A1 and atherosclerosis: An unannotated disease-specific cell cluster (A-cluster 6) co-expressed contractile VSMC markers (Myh11, Acta2, and Cnn1) with several atherosclerosis-induced ECM genes (Col1a1, Mgp, Eln, Fn1, Col4a1, and Col8a1) and had reduced levels of Ly6a, Vcam1, and Tnfrsf11b compared to imVSMCs (Figure 2A–C; Supplementary material online, Figure S1).