Snail family proteins regulate transcription of molecules for cell-cell adhesion 
during epithelial-mesenchymal transition (EMT). Based on putative glycogen 
synthase kinase 3β (GSK-3β) phosphorylation sites within the Slug/Snail2, we 
explored the significance of GSK-3β-mediated phosphorylation in Slug/Snail2 
expression during EMT. Mutation of the putative GSK-3β phosphorylation sites 
(S92/96A or S100/104A) enhanced the Slug/Snail2-mediated EMT properties of 
E-cadherin repression and vimentin induction, compared with wild-type 
Slug/Snail2. S92/96A mutation inhibited degradation of Slug/Snail2 and S100/104A 
mutation extended nuclear stabilization. Inhibition of GSK-3β activity caused 
similar effects, as did the phosphorylation mutations. Thus, our study suggests 
that GSK-3β-mediated phosphorylation of Slug/Snail2 controls its turnover and 
localization during EMT.