SPARC and neoplasm: In our study, we found that six key osteoblast regulators (ALPL, osteopontin, osteocalcin, OB-cadherin, RANKL, and SPARC) frequently exhibited copy gain and increased RNA expression in CTCs and tumor biopsies from men with bone metastases, while one key osteoblast and osteoclast regulator RUNX2 frequently exhibited copy loss in CTCs.