RA inhibited the movement of human bone-homing breast cancer cells suggesting that RA affected the bone metastasis in breast carcinoma via activation of the NF-kB ligand (RANKL)/RANK/osteoprotegerin (OPG) pathway with the simultaneous repression of the IL-8 expression (Xu et al., 2010). This evidence concerns the gene TNFRSF11A and breast carcinoma.