RUNX2 and breast cancer: These results indicate a period of latency for the cancer cells, as defined as a “pre-osteolytic stage.” However, upon direct interaction both in-vitro and in-vivo with either mouse MC3T3-E1 osteoblasts, human FOB1.19 fetal osteoblasts, or human mesenchymal stromal cells (in-vitro); or alkaline phosphatase, collagen-I, RUNX2, or osterix positive osteogenic niche cells (in-vivo), there was a statistically significant increase in breast cancer cell proliferation [161].