Fig. 1.

MyD88 promotes the formation of DMBA/TPA-induced skin papillomas. WT and MyD88^−/− mice were injected with 25 μg of DMBA and 1 week later twice weekly with 4 μg of TPA for 20 weeks as described in Materials and Methods. Mice were subsequently monitored for skin papilloma development for 25 weeks (n = 11–15 mice per group). (A) Proportion of mice in the group with papillomas over time. (B) Mean lesion number per mouse over time. Significant differences in mean lesion number per mouse were observed by the unpaired Mann–Whitney U test (*, P < 0.05). Significant differences in proportion with papilloma at any one time point were determined by Fisher's exact test (*, P < 0.05). Differences were observed at all points between the asterisks (weeks 17–25).