Diurnal analysis of osteoblast-associated mRNA expression. The expression profile of mRNA encoding the osteoblast-associated genes in the a femur and b lumbar vertebra of sham-operated (square) and OVX (diamond) mice was determined by RT-PCR using total RNA pooled from n=3 mice per time point (ZT h). The mRNA levels of Alpl, Ibsp, OPG, RANKL, and Runx2 were normalized at the individual time points relative to the housekeeping controls 18S RNA, β-actin, β2-microglobulin, and cyclophilin B. Values displayed are the mean±SD