CTLA4 and focal segmental glomerulosclerosis: Yu et al. [21] recently described five patients (four with recurrent FSGS after kidney transplantation and one with FSGS in native kidneys) who were treated with abatacept (cytotoxic T-lymphocyte–associated antigen 4–immunoglobulin fusion protein [CTLA-4–Ig]) based on positive staining for B7-1 in glomerular podocytes.