Stability ranking of select reference genes in LPS treated RAW 264.7 cells and peritoneal macrophages at 6 h and 24 h. Ct values were recorded for control and LPS (10 ng/ml) stimulated RAW 264.7 cells and peritoneal macrophages at 6 h (a-d) and 24 h (e-h). Ct values were transformed as instructed and applied to the 3 reference gene analysis softwares. The tables above show the ranking of most to least stably expressed reference genes between control and LPS stimulated cells in (a, e). RAW264.7 cells and (b, g) peritoneal macrophages, from top to bottom, as identified by Normfinder, GeNorm and BestKeeper softwares. The Ct values are plotted for LPS stimulated (c, f). RAW 264.7 cells and (d, h) peritoneal macrophages. The error bars represent means ± SDs. The significance values were calculated by comparison of control and treated samples as a group, at each time point. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001