TF cytoplasmic domain deletion impairs spontaneous breast cancer development in the PyMT model. (A) Cohorts of 29 PyMT WT, 29 PyMT TF^ΔCT, and 17 PyMT TF^ΔCT/PAR2^−/− mice were examined weekly for palpable tumors and tumor incidence was recorded. The mean time for appearance was delayed from 9 weeks for WT to 11 weeks for PyMT TF^ΔCT, and TF^ΔCT/PAR2^−/− mice (P < .0001 log-rank test). (B) Cumulative tumor burden was determined by weekly measurements of tumor volumes in all mammary glands. PyMT TF^ΔCT and TF^ΔCT/PAR2^−/− mice had reduced tumor masses relative to WT, mean ± SEM, P < .001 ANOVA Kruskal-Wallis. (C) Tumor progression in 11-13-week-old mice. Detectable tumors were harvested with a similar age distribution in each group. Fixed tumor sections were stained with Masson trichrome and tumor areas were quantified with Image Pro Plus. Tumor areas were smaller in PyMT TF^ΔCT and TF^ΔCT/PAR2^−/− relative to WT, n ≥ 10, mean ± SD, P < .05 ANOVA. Representative images, scale bar is 100 μm.