Active Aβ vaccination in APPSw/NOS2-/- mice leads to increased activity of MMP2 and MMP9 as measured by gelatin zymography. Panel A shows a representative image of the gelatin zymogram. The white bands indicate where the gelatin has been degraded by the proteinase. Based on the molecular weights of pro-MMP9, MMP9, pro-MMP2 and MMP2 we performed densitometry measurements on the white bands corresponding to these proteinases. Panel B shows the average (± SEM) densitometry quantification of the zymography bands. Data are shown as the fold-change from the average of the NOS2-/-densitometry data. Total sample size is N = 6 for NOS2-/-, N = 7 for KLH vaccinated and N = 7 for ABeta vaccinated. ** indicates P < 0.01 compared to KLH vaccinated.