ACTA1 and IgA glomerulonephritis: In contrast, a substantial number of CD68+α-SMA+ cells were present in biopsies featuring active fibrosis in fibrocellular crescents and progressive interstitial fibrosis in patients with IgA nephropathy (Figures 1b–d), indicating that MMT accounts for a substantial proportion of the myofibroblast population in active renal fibrosis.