Figure 4

Determination of the optimal number of control genes for the normalization of quantitative gene expression data in osteoblasts, macrophages and osteoclasts. Relative gene expression data were assessed by geNorm and the pairwise variations between consecutive normalization factors were calculated. V(X)/(Y) signify the variance between consecutive normalization factors. For example, V2/3 represents the variance between NF2 (geometric average of two most stably expressed genes) and NF3 (geometric average of three most stably expressed genes).