A notable feature of our prior gene expression analysis of ΔFosB and CREB overexpression in the NAc (McClung and Nestler, 2003) was the identification of a subset of genes regulated by both transcription factors. Using ChIP-chip, we found a significant 20% overlap between the cocaine-induced ΔFosB- and phospho-CREB-bound genes (Supplemental Fig. S2; Supplemental Table S12). The 20% overlap observed here is not as strong as that found in our earlier overexpression study, but this may reflect a temporal disconnect between transcription factor binding and changes in steady-state mRNA levels (e.g., co-activators are not immediately recruited) or indirect effects of CREB and ΔFosB overexpression on gene regulation. Nevertheless, many of the 323 overlapping genes, including the genes encoding AGS3, the D1 receptor, the CCKA receptor (cholecystokinin A receptor), IkBε (inhibitor of kappaB), 5-HT2AR (serotonin 2A receptor), and the NMDA2A receptor subunit (see Supplemental Table S12 for complete list) have been implicated previously in cocaine responses and likely contribute to the potent action of these two transcription factors on cocaine-induced behaviors (Carlezon et al., 2005; Nestler, 2008). The list of overlapping ΔFosB
