This study demonstrates the importance of obtaining our own expression results of OPG, RANKL, RANK, TRAIL, TRAIL-R (R1, R2, R3 and R4), SDF-1 and CXCR4 in cultures from the human BC cell lines MDA-MB-231 and MCF-7 in different culture conditions. The gene discussed is CXCL12; the disease is breast cancer.