Figure 7. p53 loss promotes the initiation and expansion of low-grade PanINs.

(a) Low-grade uniform colour PanINs from 6-week-old Pdx1-Cre-K-MADM-p53 mice showing p53^KO/KO (green, GFP+/tdTomato−), p53^WT/WT (red, GFP−/tdTomato+) and p53^KO/WT (yellow, GFP+/tdTomato+) cells. Representative images of all-green and all-red PanINs are shown. Blue, DAPI-stained nuclei. Scale bars, 100 μm. (b) Absolute quantification of observed all-green and all-red low-grade PanINs from 6-week-old Pdx1-Cre-K-MADM-p53 mice (n=5 mice total). Expected numbers are based on 1:1 stoichiometric ratio of green and red cell generation, and were not observed (P<0.001, χ²-test). (c) Low-grade mixed-colour PanINs from 6-week-old Pdx1-Cre-K-MADM-p53 mice showing green, red and yellow cells. Representative images of non-dominant, green-dominant and red-dominant low-grade PanINs are shown. Blue, DAPI-stained nuclei. Scale bars, 100 μm. (d) Absolute quantification of observed green-dominant and red-dominant low-grade PanINs from 6-week-old Pdx1-Cre-K-MADM-p53 mice (n=5 mice total). Expected numbers are based on 1:1 stoichiometric ratio of green and red cell generation, and were not observed (P<0.001, χ²-test). A minority of low-grade PanINs (14 of 94) did not exhibit color dominance.