STAT3 and cancer: Commensal microbes stimulate the production of cancer-associated-cytokines that often have deleterious consequences for tumor progression via activation of the interleukin-23 (IL-23)-IL-17 axis [129], the TNF-α/TNF receptor axis [55, 130], IL-6 family signaling [55, 66, 130], IL-10, IL-8, IL-18, monocyte chemoattractant protein-1 (MCP-1) [125, 132], signal transducer and activator of transcription 3 (STAT3) [55, 133], and the production of ROS [88] and nitrogen species (NS) [38, 120].