Pdx1 Is Expressed in the Skin Figure 1. Pdx1-Cre;Kras;N1ko mice develop skin tumors. A: Kaplan-Meier tumor-free survival analysis of Pdx1-Cre mice. B: Table summarizing survival and skin tumor incidence observed in Pdx1-Cre mice. C: PCR results confirm Notch1 deletion and KrasG12D activation in pancreas and skin papilloma while non-recombined status in unaffected skin, liver and in WT control DNA. D: Examples of skin neoplasia observed: papillomas of neck- head and ear (i), sebaceous gland tumor (ii), cutaneous horns (iii, black arrowhead) and SCC (iii, white arrow). E: Hematoxilin and eosin staining (HE) of WT skin (i) and characteristic cutaneous histopathologies found in Pdx1-Cre;Kras;N1ko mice: hyperplasia (ii), skin papilloma (iii) and SCC (iv). F: X-Gal staining indicates Cre-mediated recombination in skin hyperplasia (left) and papillomas (right) of Pdx1-Cre;Kras;N1ko;ROSA26R-LacZ reporter mice. The scale bars represent 50 mm. doi:10.1371/journal.pone.0013578.g001 PLoS ONE | www.plosone.org 3 October 2010 | Volume 5 | Issue 10 | e13578