TIMP4 and Alzheimer disease: In addition, the mRNA expression of TIMP-4 was significantly lower in the RKIP-RNAi-AD group (0.19±0.17) compared with the NC-RKIP-RNAi-AD group (1.00±0.00) (P<0.05; Fig. 5E), and higher in the RKIP-AD group (2.13±0.60) compared with the GFP-AD group (1.00±0.00) (P<0.05; Fig. 5F).