Supplemental Figure S1.

Representative images of wild-type mouse bladder urothelium 4 hours after cyclophosphamide injection. A: Hematoxylin and eosin–stained bladder shows sloughing of urothelial cells (arrows). B: KRT20 immunofluorescence (IF; red) in a section adjacent to A shows that the sloughing cells are still KRT20⁺ superficial cells (arrow) and that larger regions of remnant urothelium have attenuated (arrowhead) or no KRT20 expression. C and D: Uroplakin 3a (UPK3) IF (white; C) and KRT5 IF (green; D) in a section adjacent to B shows rare regions of discontinuous urothelial staining for both markers (arrows). E: Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining (green) in a section adjacent to C and D is now positive in a few nuclei (arrowheads) consistent with the onset of apoptosis in deeper urothelial; cells. Dotted lines indicate demarcation between urothelial layer and underlying lamina propria. B–E: Blue indicates DAPI. Scale bar = 50 μm (A–E). L, lumen.