CTLA4 and focal segmental glomerulosclerosis: Yu et al. showed the resolution of nephrotic range proteinuria after B7-1 inhibition with Abatacept (CTLA-4–Ig) treatment in patients with rituximab-resistant recurrent FSGS and in patients with glucocorticoid-resistant primary FSGS (18), suggesting that B7-1 can be a target for the treatment of proteinuria.