STAT3 and neoplasm: In addition to immune escape, infiltrating macrophages contribute to tumor formation and maintenance through production of cytokines RANTES and TNF‐a, which mediate acinar‐to‐ductal metaplasia, secretion of IL‐6 promoting tumor progression through STAT3 signaling, and by overexpressing cytidine deaminase, which inactivates gemcitabine (Liu et al, 2013).