Figure 2: (a) shows a traditional photographic image (RGB) of the slide. Following "unmixing," (b) demonstrates CK20 staining limited to the umbrella cells/upper 1/3 of the urothelium and (c) shows the P53 staining. (d) shows a composite of the unmixed stains re-assigned with different colors for easier interpretation. This case was graded as 2+ for P53 and 1+ for CK20. The diagnosis given was reactive urothelium.