STAT3 and familial pancreatic carcinoma: Additionally, differences in phosphorylation residues can cause cells to mount alternative responses to autophagy; in pancreatic cancer, secreted IL-6 induces p-STAT3 at Ser727, which was an important residue for its mitochondrial localization, whereas in this study, STAT3 activation was marked by its phosphorylation at Tyr705.