Specificity controls in the clustering process. (a) Statistical significance of clusters. Bar plots representing the number of clusters observed in the set of genes regulated by TRX (up-regulated clusters in red, down-regulated clusters in green) and the number of clusters expected by chance (in white). The number of trx clusters observed in each chromosome was highly significant (Z-score >2). Error bars represent the standard deviation of the random samples. (b) Quantitative RT-PCR of target expression (clusters 4 and 20) in third instar wild-type (WT) and trx mutant larvae. Error bars represent variability between replicates.