SPP1 and breast cancer: Compared to vehicle-treated osteoblasts, osteoblasts “educated” with the conditioned medium of hTERT-HME1 cells (EO-HMEC) or MDA-MB-231, MDA-MB-231BRMS, or MCF-7 breast cancer cells (EO-231, EO-BRMS, and EO-MCF7, respectively) exhibited minimal to no change in the expression of osteopontin (Fig. 2a).