Hormone therapy effects on gene markers of RANK/RANKL signaling. (a) mRNA expression of RANK, RANKL, and the endogenous inhibitor of RANKL signaling (OPG) and (b) ratios between these markers. mRNA levels were determined by quantitative PCR and expressed as (a) relative means or as (b) ratios of RANK/OPG or RANKL/OPG. Vertical lines indicate 90% confidence interval. Letters indicate significant differences between groups as indicated.