In a second approach, the gene expression profile in livers of the above mentioned mice was compared by Affymetrix GeneChip® Mouse Genome 430 2.0 Arrays (Table 1). When analyzing the probe array data of livers from mock-treated Mtf1Mx-cre and Mtf1loxP mice, an at least 2-fold, reliable downregulation of expression was detected in Mtf1Mx-cre livers for 13 Affymetrix GeneChip® probe sets corresponding to 11 characterized genes (Table 1, a). Seven of these genes contain one or more MRE core consensus sequence TGCRCNC within a segment of 1000 bp upstream of the transcription start. For 26 probe sets corresponding to 24 different characterized genes, a 2-fold or higher, reliable upregulation was detected in Mtf1Mx-cre livers (Table 1, b); 17 of these 24 genes contain MRE core consensus sequences in the upstream region. The data set for livers of cadmium-treated Mtf1Mx-cre and Mtf1loxP mice revealed an at least 2-fold, reliable downregulation in Mtf1Mx-cre livers for 21 probe sets corresponding to 16 different characterized genes (Table 1, c); 10 of these contain MRE core consensus sequences in their upstream region. For 9 probe sets corresponding to 9 different characterized genes, an at least 2-fold, reliable upregulation was detected (Table 1, d); five of them contain MRE motifs. In addition to characterized genes, ESTs and RIKEN cDNA sequences were also found in the comparison of Mtf1Mx-cre and Mtf1loxP livers to be differentially expressed (Supplementary Table 1). Downregulation of Mt1 and Mt2 was detected in Mtf1Mx-cre livers for both conditions (though the level of significance for the downregulation of Mt1 in mock-treated animals was above 0.05; data not shown).