Breast Cancer PAR2 signaling promotes tumor growth and angiogenesis. (A) Typical experiment of orthotopic tumor growth of C57BL/6 mammary fat pad implanted mock, PAR2^WT, or PAR2^ΔARR transduced PyMT PAR2^−/− breast cancer cells (5 × 10⁵/mouse). Tumor volumes are mean ± SD, n ≥ 7 mice/group, P < .05 different from mock by ANOVA. (B) Final tumor weights from 3 independent experiments, mean ± SD, n ≥ 7 mice/group, *P < .05; #P < .001 different from mock by ANOVA. (C) Vessel density of mock, PAR2^WT, or PAR2^ΔARR tumors was determined on fixed sections stained with CD31. Tumor vessels were quantified with the IMARIS software in at least 4 different areas per tumor, and at least 4 mice/genotypes were analyzed, mean ± SD, * different from mock tumors, P < .05, ANOVA, scale bar 50 μm. (D) Tumor macrophage density was quantified in 4 fields per tumor (n ≥ 3, mean + SEM, P = .5 ANOVA). (E) Phospho Histone 3 and DAPI staining were quantified in at least 4 fields of view with the IMARIS software (n ≥ 4, mean ± SEM, P = .4 ANOVA).