To determine the impact of bone metastatic breast cancer cells on osteocytes, we crossed NuTRAP reporter mice (21), a Cre-inducible strain that allows labeling and simultaneous isolation of cell type-specific nuclei (mCherry) and mRNA (GFP), with Dmp1-8kb-Cre mice to induce active Cre recombination in osteocytes (22). Here, DMP1 is linked to breast cancer.