However, since FSGS mainly recurs early after KT, pre-existing circulating factors, such as soluble urokinase plasminogen activator receptor, cardiotrophin-like cytokine factor-1, apolipoprotein A-lb, and anti-CD40 antibodies, are considered to play important roles in recurrent FSGS [3]. Here, CLCF1 is linked to focal segmental glomerulosclerosis.