ATF3 and focal segmental glomerulosclerosis: Next, we validated upregulation of ATF3 in renal biopsies from patients with different fibrotic renal diseases, including membranous nephropathy, IgA nephropathy, focal segmental glomerulosclerosis, anti-neutrophil cytoplasmic antibodies-associated vasculitis, and diabetic nephropathy, in comparison to normal kidney tissues by IHC (Fig. 1A).