fig4

Figure 4. E₂ effects on histologic tumor burden and tumor cell proliferation in bone. (A) Cytokeratin-positive breast cancer tumor area in hind limbs, normalized to bone area in mid-sagittal sections, 6 weeks post-ER+ tumor cell inoculation of 5- or 16-week old mice. There was no linear trend in tumor burden with increasing E₂ doses, and no significant differences (n.s.) between E₂ doses, or between young and mature mice treated with 0.72 mg E₂, as tested by 1-way ANOVA with Sidak post-test (n = 3-9/group). (B) Proliferating, Ki67-positive cells in hind limb breast cancer tumors (% of total) 6 weeks post tumor-inoculation. There were no significant differences (n.s) in the proportion of Ki67-positive tumor cells between E₂ doses [including the lowest (0.05 mg) and highest (0.72 mg)], or between young (5-week) and mature (16-week) mice treated with 0.72 mg E₂, as calculated by 1-way ANOVA with Sidak post-test (n = 8-18/group).