SCRIB and papilloma: IHC to detect BrdU incorporation revealed that bi-allelic Scrib loss causes a small, yet significant increase in the number of mitotic cells (37.3 % ± 1.754 SD) compared to Scrib+/fl (32.3 % ± 1.742 SD) or Scrib+/+ (33.1 % ± 0.991 SD) papillomas (Fig. 6c and d).