NOX4 and focal segmental glomerulosclerosis: In focal segmental glomerulosclerosis (FSGS), the level of NOX4, a subunit of NOX complex, is higher in patients with steroid-resistant nephrotic syndrome (SRNS) than those with steroid-sensitive nephrotic syndrome, and the level of ROS is also higher in the glomeruli isolated from patients with SRNS [35].