RUNX2 and neoplasm: An essential regulator of skeletal development, Runx2 is highly expressed in breast cancer skeletal metastases, and is associated with tumor-induced osteolysis. Runx2 activity is promoted via the PI3K/AKT signaling pathway. Evidence shows that expression in bone metastasis is regulated by miR-135 and miR-203. Functions also in increasing cell proliferation via disrupting growth-arresting acini structures, and promoting cell survival by enhancing the autophagic process.