CD44 and focal segmental glomerulosclerosis: On one hand, it was reported that PECs migrate onto the glomerular tuft and participate in glomerular scar formation by extracellular matrix deposition, characteristically proliferating and expressing the activation marker CD44 (Smeets et al., 2014; Roeder et al., 2017), and this was also confirmed in focal segmental glomerulosclerosis in allograft human biopsies (Fatima et al., 2012).