MAPT and tauopathy: Given the accumulation of overt NFT-like pathology in rTg4510 mouse brains by 9 months (the age of animals employed in this study) and the fact that Tau caspase cleavage is an event linked with Tau pathology, D421 epitopes were anticipated to be present at high levels in brain sections from both rTg4510 mice and human tauopathy donors.