Fig. 3

Distribution of P values and FC values of gene expression before and after quercetin treatment. a Kernel density estimates of P values obtained from 10 cycles of 100 permutations. P value was obtained by using Kolmogorov–Smirnov test between two sets of 36 FC values. Prandom denotes the distribution of P values for two sets of 36 randomly selected genes. Pempirical denotes the distribution of P values obtained by comparing the empirical FC values to the random set. Illustration suggests that FC induced by quercetin is significantly different than might be expected by chance. b Kernel density estimate of log FC of quercetin and the background set. Illustration suggests that quercetin tends to induce expression levels. Quercetin denotes the FC values of 36 cell-cycle genes. Background denotes the FC values of 16,308 genes (P = 0.02, Kolmogorov–Smirnov test)