By using a series of in vivo-selected MDA-MB-231 breast cancer cell populations that are metastatic to bone and lung, we demonstrated that ABCC5 expression was highest in bone metastatic cell populations (1833-BM1) when compared with lung metastatic cells (4175-LM2) or the parental MDA-MB-231 cell line (Figure 3A). This evidence concerns the gene ABCC5 and breast cancer.