Delayed overexpression of neuronal Rac1 promoted functional recovery after ischemic stroke in mice. Highly concentrated lentivirus encoding Rac1 with neuronal promotor NSE was injected into both the cortex and striatum of WT mice at day 7 after stroke. Same process was performed using lentivirus without Rac1 sequence as controls. (A) Immunohistochemistry assessment of cerebral Rac1 expression (red, Alexa Fluor 647) on neurons (NeuN, green, Alexa Fluor 594) 28 days after stroke (N = 4/each group). Arrows indicated the Rac1 positive neurons (yellow). Functional recovery assessed by (B) novel object recognition test, (C) adhesive removal test and (D) pellet reaching test before (Pre) up to 28 days after stroke (N = 8 in the control vector group, N = 9 in the NSE-Rac1 group). N = number of animals. *p < 0.05, **p < 0.01, ***p < 0.001. Mann-Whitney test was used for immune-staining. Two-way ANOVA with subsequent Bonferonni test was applied for behavioral tests.