MAPT and Alzheimer disease: N-terminal tau fragments have been found in several in vitro and in vivo models, such as in primary neuronal cultures undergoing apoptosis (Canu et al., 1998; Park and Ferreira, 2005), in the cerebrospinal fluid (CSF) of rats after traumatic brain injury (TBI), in transient forebrain ischemia (Siman et al., 2004), and in brain tissue of AD patients (Rohn et al., 2002).