TNFRSF11B and cancer: Surprisingly, OPG reduced osteoclast numbers by only 27.7% ± 5.14% in the culture with mtMDA CM and 49.3% ± 14.10% in the culture with MDA CM (Fig. 1d), indicating that RANKL was not the sole factor responsible for the stimulatory effect of these cancer cells on osteoclastogenesis.