NTN1 and nervous system disorder: We observed differential mRNA expression of a number of other genes with known or putative roles in brain biology/addiction, but not previously reported for methamphetamine exposure: Slc47a2 which is a multi-drug and toxin extrusion transporter that removes organic cations and interacts with organic cation transporters [35]; Slc9a6 (NHE6) which has a role in neurological disease and axon and dendrite branching [36], and Netrin-1 which is involved in axon guidance and is important in both brain development and adult brain function.