Figure 1.

Single control normalization error values (E) were calculated as the ratio of the ratio of two control genes in two different samples (see Materials and methods), and summarized here as cumulative distribution plots for the different tissue panels, pointing at considerable variation in housekeeping gene expression.

Vandesompele et al. Genome Biology 2002 3:research0034.1-research0034.11   doi:10.1186/gb-2002-3-7-research0034