ACP5 and Familial prostate cancer: However, in line with the inhibitory effects by TRAMP-C1 tumor cell-derived exosomes on osteoclastic differentiation of RAW264.7 cells, treatment of primary osteoclast precursor cells with prostate cancer exosomes also resulted in a distinct decrease in the number of TRAP-positive, multinucleated osteoclasts formed in the presence of the higher concentration of exosomes used (50 ng/103 seeded cells; Fig 4B).