Figure 6. Rnf144a KO mice show lower EGFR expression in normal urothelium and BBN-induced bladder tumors compared to WT mice.

(A) Western blot analysis demonstrates lower EGFR protein expression in the bladder tissue of Rnf144a KO mice compared to WT mice. #1 and #2 represent different mice of each genotype.

(B) In the BBN-induced premalignant lesions of Rnf144a KO mice, loss of EGFR is found in the basal layer between EGFR-positive intermediate cells and the lamina propria. Immunohistochemical staining was performed to detect EGFR expression in the urothelium of untreated and BBN-treated WT or Rnf144a KO mice. Panel 4 shows higher magnification of the boxed area in panel 3. Data shown are representative images (N=6 per group).

(C) Immunohistochemical staining shows the loss of EGFR in malignant lesions of BBN-treated Rnf144a KO mice. Shown are two representative images of Rnf144a WT or KO mice (N=6 per group).

(D) Immunohistochemical staining of EGFR in Rnf144a KO tumors shows that the loss of EGFR is only found in the cancerous area but not in adjacent normal tissues. Black arrows indicate normal urothelial cells with EGFR expression. The left panel shows 5X magnification, and the right panel shows 20X magnification of the boxed area in the left panel. Data shown are representative images (N=6).

(E) Immunohistochemical staining of EGFR, p63, or CK14 in the urothelium of BBN-treated Rnf144a KO mice (N=6). Data shown are representative images. Black scale bars represent 20 μm. Red scale bars represent 100 μm.