RAC1 and focal segmental glomerulosclerosis: Soluble urokinase plasminogen activator receptor (suPAR) is another proposed damaging circulating factor in FSGS,58 which binds to podocyte plasminogen activator receptor and modulates the activity of the cytoskeletal proteins Ras homolog family member A and Rac1 in a cellular human podocyte model of FSGS.59