Presenilin 1 (PS1), a causative molecule of familial Alzheimer's disease (AD), is known to be an unprimed substrate of glycogen synthase kinase 3 β (GSK3β) [Twomey and McCarthy (2006) FEBS Lett 580:4015-4020] and is phosphorylated at serine 353, 357 residues in its cytoplasmic loop region [Kirschenbaum et al.(2001) J Biol Chem 276:7366-7375].