TNFRSF11B and arthritic joint disease: To understand the mechanism of the suppression of arthritis in 5C6-treated KO1 mice, transcription levels of RANK, RANKL, OPG, and several important arthritis-related cytokines in ankle joint tissues were compared among the three groups of mice by qRT-PCR analysis using mRNA extracted from tarsal bones of the mice at 10 months old.