PCa cells expressing Ac-KLF5 also caused osteoclastogenesis, as indicated by a dramatic increase in TRAP-positive multinucleated osteoclasts in tibias (Fig. 4a, b) and TRAP + cells in the RAW264.7 in vitro model of osteoclastogenesis (Fig. 4c–h). Here, ACP5 is linked to posterior cortical atrophy.