Previous reports have shown that the IBSP promoter contains a fibroblast growth factor 2 response element (−96 to −89) and a homeodomain protein-binding site (HOX; −200 to −191) [56,57], but the involvement of HOXB13 in IBSP promoter regulation is a novel finding, denoting the importance of the HOXB13/HOXA11-AS axis in prostate cancer bone metastasis. This evidence concerns the gene FGF2 and Familial prostate cancer.