IL6 and esophageal squamous cell carcinoma: Whereas STAT3 is not described as a direct substrate, inhibition of GSK3β after stimulation with IFN-γ, IL-6, or IFN-α reduces the phosphorylation of STAT3 on Y705 (Beurel and Jope, 2008), and GSK3β modifies STAT3 phosphorylation in esophageal squamous cell carcinoma (Gao et al., 2017).