PECAM1 and renal fibrosis: Using three mouse models of chronic kidney disease, unilateral ureteral obstructive (UUO) nephropathy, streptozotocin (STZ)‐induced DKD and Alport nephropathy, Zeisberg et al.7first tested the role of EndMT in renal fibrosis in 2008 and found that about 30%–50% of fibroblasts co‐express the endothelial marker CD31 and fibroblast markers such as α‐smooth muscle actin (α‐SMA) and fibroblast‐specific protein‐1(FSP‐1), indicating that these fibroblasts originate from endothelium cells.