PTK2B and Alzheimer disease: It has been previously found that STriatal-Enriched protein tyrosine Phosphatase (STEP) is increased in AD, and opposes the development and strengthening of synapses via dephosphorylating and inactivating synaptic proteins including kinases such as Fyn, Pyk2, and ERK1/2 (Venkitaramani et al., 2009; Xu et al., 2012; Li et al., 2014).