Increased expression and activity of GSK3β in ESCC cells was also supported by the finding that S641 phosphorylation of GS (pGSS641, inactive form), the primary substrate of GSK3β15,16, was higher in ESCC than in TYNEK-3 cells (Supplementary Information, Fig. S2A). This evidence concerns the gene GSK3B and esophageal squamous cell carcinoma.