An increase in iNOS protein expression has been proved after cerebral ischemia in this paper, which is consistent with that in vivo DAHP can reduce cerebral infarction via inhibiting iNOS activity and ONOO level in transient focal ischemia, and iNOS inhibitor can protect against neuronal injury in ischemic stroke (Kolinsky and Gross, 2004; Kidd et al., 2005). Here, NOS2 is linked to cerebral infarction.