Regulation of candidate reference genes in anti-CD3/CD28 activated T cells (A) and LPS-stimulated neutrophils (B). Shown are log2 fold mRNA changes of candidate reference genes or combinations of them in stimulated compared to non-stimulated cells. Data are normalized to a normalization factor based on the geometric mean of the three best performing candidate genes according to geNorm, NormFinder and BestKeeper. Results are given as mean ± SEM of n = 6 (A) or n = 7 (B) paired samples. Unfilled circles indicate candidate genes ruled out as suitable normalizers beforehand due to significant differences (p < 0.05) in raw Cq values in paired samples of unstimulated and stimulated cells (see Figure 1).