Additionally, AD brains show increased APP phosphorylation at Thr668, which is known to be phosphorylated by kinases such as GSK-3, cdk5, ERK, JNK, and cdc2 (Suzuki et al. 1994; Aplin et al. 1996; Iijima et al. 2000; Standen et al. 2001; Muresan and Muresan, 2005; Judge et al. 2011). Here, CDK5 is linked to Alzheimer disease.