RUNX2 is upregulated in metastatic breast cancer cell lines (Barnes et al., 2003; Nagaraja et al., 2006) and its inhibition in MDA-MB-231 cells reduces invasive capacity in vitro, and decreases osteolytic disease and tumour growth in vivo (Barnes et al., 2004; Javed et al., 2005; Pratap et al., 2009). This evidence concerns the gene RUNX2 and breast cancer.