CREB1 and Alzheimer disease: Additionally, a study on a mouse model of AD found that TGF-β1 improved the expressions of synaptic plasticity-related proteins including Arc, NR2B and PSD-95, as well as spatial memory through activating PI3K/Akt pathway [81], and several other studies proved that TGF-β1 increased CREB phosphorylation which is involved in various forms of synaptic plasticity and memory [82, 83].