Quantitative immunostaining for SMOC2 (red) and αSMA (green) was performed on kidney sections obtained from mice at day 7 following (A) unilateral ureteral obstruction (UUO) or (B) folic acid injection (FA) (n = 5; 20× magnification). Scale bar: 50 μm. For the UUO model, contralateral kidney (CoK) tissue from day 14 was also included. Bottom panel in A shows magnified images taken at 40× from the selected regions of the middle row. Scale bar: 30 μm. Relative quantitation of SMOC2 and αSMA immunofluorescence, as represented in a box plot, was performed using representative images of 5 visual fields for each tissue analyzed. (C and D) Representative Western blot (n = 5/condition; Supplemental Figure 1, B and C [UUO and FA, respectively]) of SMOC2, αSMA, collagen 1α1, and fibronectin expression using kidney samples obtained from mice subjected to 7 and 14 days of UUO or FA. (E) Quantitative immunostaining for SMOC2 (red) and αSMA (green) in human kidneys with pathological fibrosis underlying chronic kidney disease (CKD) (n = 5) and nonfibrotic patients (n = 5; 20× magnification). Yellow scale bars: 50 μm. Bottom panel shows magnified images taken at 60× from the selected regions of the middle row. White scale bars: 25 μm. Relative quantitation of SMOC2 and αSMA immunofluorescence as represented in a box plot was performed using representative images of 5 visual fields for each tissue analyzed. (F) Urinary levels of SMOC2 and kidney injury molecule-1 (KIM-1) normalized to urinary creatinine were measured in patients with CKD (n = 13) compared with healthy volunteers (n = 13). Box plots describe the median (line within box), upper and lower quartiles (bounds of box), and minimum and maximum values (bars). *P < 0.05 determined by t test. Yellow arrows, tubules. White arrows, interstitium.