MMP9 and Alzheimer disease: An interesting experimental approach has been reported by Yan et al. (2006), who prepared 5 μm thin snap frozen cryostat sections from saline perfused AD mice (APP/PS1), incubated them in 70 nM protease (MMP-9, ECE, IDE, NEP) at 37°C for 5 days and stained them with Thioflavin S and observed degradation of plaques by MMP-9 only.