Gene expression in unexposed young mice relative to adults of the same sex. A, Gene enrichment for selected relevant disease and disorder functions with significance as determined by IPA software using Fisher’s exact test. Threshold for significance is set at –log (0.05). B–D, Heatmaps for groups of genes associated with B, lung tumors, C, DNA damage, or D, repair of DNA. E–F, Genes associated with lung tumors or DNA damage/repair with IPA prediction of activation (orange) and inhibition (blue), and with observed increases (red) or decreases (green) in young female animals relative to female adults. Gene expression is lower in neonates than adults for most genes of interest. Gene expression is similar between juveniles and adults for most genes of interest; however three genes (Agr2, Cdkn1c, Ptgs2) have increased measurement and three (Sftpc, Hnmt, Gstp1) have decreased measurement.