MX1 and influenza: Since the expression level and phosphorylation of the transcription factor STAT1 play a critical role in the regulation of type I IFN signaling, and myxovirus resistance protein (MxA) is an important IFN-inducible gene product in fighting influenza infections [29], we intend to know whether the reduction of influenza replication in meth-exposed cells is related to the up-regulation of these antiviral mediators.