CD9 and cirrhosis of liver: have highlighted the utility of single-cell RNA-sequencing in dissecting mechanisms regulating human liver cirrhosis by uncovering 3 novel subsets involved in the pathogenesis of liver fibrosis including TREM2+CD9+ macrophages, ACKR1+ and PLVAP+ endothelial cells and PDGFRα+ collagen producing myofibroblasts [27].