Interestingly, H1 is a substrate of p25/Cdk5 that accumulates in AD patients (Patrick et al., 1999; Chang et al., 2012) and is associated with neurodegeneration and cellular damage such as false entrance of cell cycle division (Cruz et al., 2006), and H2A.X phosphorylation (Kim et al., 2008), both pathophysiological characteristics of AD (Ogawa et al., 2003; Myung et al., 2008). The gene discussed is CDK5; the disease is Alzheimer disease.