RARA and focal segmental glomerulosclerosis: In FSGS mice, most PECs showing RA/RAR activity are outside FSGS lesions while most of those within FSGS lesions do not respond to RA and do not differentiate into podocytes, suggesting that in addition to albuminuria, other local molecular and cellular factors in the FSGS niche may also affect RA/RAR signaling in the PECs [21].