Podocyte-specific proteins colocalize with the activated parietal epithelial cell (PEC) marker CD44 in mice with experimental focal segmental glomerulosclerosis (FSGS). Double staining was performed for CD44 (red) and podocyte-specific extracellular matrix proteins (green). A−C: normal mice. The merged images show staining for laminin-β2 (LAMB2; A), agrin (B), and collagen type IV-α4 (COL4A4; C) but not CD44 in normal glomeruli. A1−C3: individual stains for LAMB2 (A1−A3), agrin (B1−B3), and COL4A4 (C1–C3). D−F: FSGS mice. The merged images show colocalization (yellow) of CD44 in PECs with LAMB2 (D and D3) and agrin (E and E3) but not COL4A4 (F and F3). D1, D2, E1, E2, F1, and F2: corresponding single stainings for LAMB2 (D1 and D2), agrin (E1 and E2), and COL4A4 (F1 and F2). Single and merged higher magnifications of the insets are shown in D4–F6). These results are consistent with activated PECs expressing the podocyte-specific extracellular matrix proteins LAMB2 and agrin in FSGS. Original magnification: ×400. Scale bars = 20 μm.