In the present study, we used our podocyte FAC assay to screen 96 SRNS/FSGS serum samples to identify the subset of patients who display podocyte toxicity, estimate the percentage in whom this can be reversed in vitro by TNFα blockade, and ascertain whether podocyte toxicity correlates with the serum TNFα level. Here, TNF is linked to focal segmental glomerulosclerosis.