ING1b and GADD45a are nuclear proteins involved in the regulation of cell growth, apoptosis and DNA repair. We found that ING1b and GADD45a physically and functionally interact in the epigenetic regulation of specific target genes. In order to study this interaction further, we analysed the transcriptional changes in MEF cells from single and double Ing1/Gadd45 knockout mice via microarray profiling. Overall design: Mouse embryonic fibroblasts (MEF cells) were isolated from embryonic day E15.5 male embryos, either wild-type (WT) or knockout for Ing1 (Ing1-/-), Gadd45a (Gadd45a-/-) or Ing1/Gadd45a (double knockout, DKO), and cultured for 3 passages. Samples were then collected in duplicates per MEF line for expression array profiling.