The amount of active MMP3 was barely detected in extracts from control brains, but there was a substantial increase in the active/mature form in all the samples from neurodegenerative diseases: FTDP-17T with the +3 and the P301L mutations were elevated 4.7-fold (P = 0.013) and 4.5-fold (P = 0.043), respectively (ANOVA P = 0.04, two-tailed t test compared to control), while the ratios were slightly lower for C9orf72 (1.78-fold, P = 0.003), PSP (2.45-fold, P = 0.019), and Pick’s disease (3.07-fold, P = 0.025) (ANOVA P = 0.012, two-tailed t test compared to control) (Fig. 6D). Here, MMP3 is linked to neurodegenerative disease.