In contrast to the ubiquitous expression of Pdx1 in the suprabasal layers of the skin, Pdx1-Cre;Kras,N1ko mice developed skin papillomas and other cutaneous lesions only in preferred sites suggesting that Cre-mediated recombination may be mosaic and/or occurs in the cells resistant to neoplastic transformation. This evidence concerns the gene PDX1 and skin papilloma.