KEGG annotation revealed that mRNAs differentially expressed in the mutant mouse cerebrum were enriched in a number of signaling pathways including tyrosine metabolism, transcriptional mis-regulation in cancer, thyroid cancer, serotonergic synapse, retrograde endocannabinoid signaling, PI3K-Akt signaling, Parkinson’s disease, nicotine addiction, neuro-active ligand-receptor interaction, morphine addiction, dopaminergic synapse, cocaine addiction, circadian entrainment, cholinergic synapse, cAMP signaling, calcium signaling, amphetamine addition, and alcoholism (Figure 3b). This evidence concerns the gene AKT1 and nicotine dependence.