Fig. 1. Keratinocyte-specific Cre expression leads to pRb ablation in vivo. (A) Schematic representation of the wild-type, the floxed (F19) and the inactivated Rb allele (19). Exons are indicated as numbered boxes and loxP sites as triangles. Rb18 and Rb19 indicate the primers used to characterize the different Rb alleles. (B-E) ß-Galactosidase staining (blue) identifies Cre activity in X-Gal stained tissue sections from epithelia of double transgenic R26R:K14cre animals in epidermis (B), tongue (C), thymic epithelium (D) and hard palate (E). (F) Cre-mediated recombination detected by PCR analysis on tails Rb^F19/F19;K14cre mice. (G) Immunoblot analysis for pRb in Rb^F19/F19 keratinocytes 48 hours post-infection with Ad-GFP or Cre-coding adenovirus. (H) Immunoblot analysis for pRb family members on primary keratinocytes derived from newborn mice with the indicated genotypes. Scale bars: 150 µm.