SP7 and neuroendocrine neoplasm: Furthermore, specific conditional ablation of both Rb and Trp53 in osteoblast precursors using an osterix promoter-Cre deleter strain induced in 75% of the double knock-out mice metastatic osteosarcomas but, most remarkable, in 60% of the mice metastatic neuroendocrine tumors were detected as well [31].