Validation of alternate exon usage array data by qPCR. Two primer-probe sets were designed for each transcript, one to an area of constant expression (control, C), the second to region showing alternate exon usage (D). Comparative quantification was calculated using the ∆∆Ct method with the control primer data being used as the endogenous normalizer. Ct levels are inversely proportional to the amount of target RNA in the sample. Comparison of daily profiles with signal intensities in Figure 5-7 shows good result concordance.