Iwasaki et al. (1995) demonstrated that hepatocellular carcinoma cells acquire the ability to metastasize in the G1 phase of the cell cycle. In prostate cancer, by inhibiting the G1-to-S phase transition of the cell cycle, Runx2 promotes the invasiveness and bone metastasis (Baniwal et al., 2010). Also, the significant relationship between invasive cells and the G1/G0 cell cycle state is observed in breast cancer metastasis (Qian et al., 2013). This evidence concerns the gene RUNX2 and breast cancer.