PTPA and Alzheimer disease: PP2A enzymes can also associate with protein kinases that have been linked to AD, such as glycogen synthase kinase 3β (GSK3β) and cyclin-dependent kinase 5 (cdk5; Plattner et al., 2006), and neuronal receptors, e.g., the NMDA receptor (Chan and Sucher, 2001) and the metabotropic glutamate receptor 5 (Mao et al., 2005; Arif et al., 2014).