CTLA4 and focal segmental glomerulosclerosis: Cytotoxic T-lymphocyte-associated antigen 4-immunoglobulin fusion protein (CTLD4-Ig, abatacept) has been tested on the basis that B7-1 (CD80) induction on podocytes plays an important role in the pathogenesis of proteinuria [64] and could eradicate proteinuria in recurrent FSGS [65]; however, the long-term efficacy of this agent has not been confirmed [66].