Overexpression of MKP-1 by AAVMKP-1 led to a marked reduction in the levels of Aβ40 (WT: 21.56 ± 11.44 pg/mg; AD + AAVEGFP: 288.67 ± 56.03 pg/mg; and AD + AAVMKP-1: 125.30 ± 39.61 pg/mg) (p = 0.025; Fig. 5f) and Aβ42 (WT: 52.70 ± 10.40 pg/mg; AD + AAVEGFP: 221.15 ± 34.02 pg/mg; and AD + AAVMKP-1: 121.03 ± 22.95 pg/mg) (p = 0.049; Fig. 5g) in the mouse brains. This evidence concerns the gene DUSP1 and Alzheimer disease.