MAPT and tauopathy: Studies have demonstrated that PAD exposure is an early event in multiple tauopathies, co-localizing with tau oligomers and AT8 immunoreactivity (Kanaan et al., 2011; Kanaan et al., 2012; Cox et al., 2016; Kanaan et al., 2016), but the question of whether the PAD also has a physiological role was unknown.