The impact of host MMP-2 on mammary tumor growth in the bone was analyzed by immunohistochemical staining for Mcm2 (proliferation) and cleaved caspase-3 (apoptosis) at the day 3 time point since this was consistently the first time point when tumor growth differences were noted between the wild type and MMP-2 null animals. This evidence concerns the gene MCM2 and breast cancer.