Integrin β3 is preferential induced on breast cancer cells within the bone microenvironment. (A) Immunohistochemistry for β3 on PyMT-Bo1 mammary tumors or metastases, established by orthotopic or intracardiac injection into separate cohorts of mice, respectively. Tumors were removed 12 days post-injection. Representative images (left), quantification of DAB-stained tumors (right), n=4 per group. Scale=50 μm. One-way ANOVA with Tukey’s post-hoc test, **** P<0.0001. (B,C) Mammary tumors or bone metastases were established as previously described. Isolated tumor cells were identified based on cytokeratin 18 expression (CK18+) and evaluated by flow cytometry for surface β3 expression. Representative samples (left). (B) PyMT-Bo1 cells, 13 days post-injection, n=3 mammary, n=4 bone. (C) 4T1 cells, 15 days post-injection, n=5 mammary, n=4 bone. Two-tailed unpaired t-test, *** P<0.001, ** P<0.01. Data presented as mean±SEM.