In particular, interleukin-6 (IL-6) has been shown to play an important role in triggering STAT3 activation via JAK (Janus Kinase) stimulation in tumor cells and other tumor-infiltrating cell populations (i.e., immune cells), with a negative regulatory effect on dendritic cells, natural killer cells, effector T cells, and neutrophils, while positively regulating regulatory T cells and myeloid-derived suppressor cells [32,33]. This evidence concerns the gene STAT3 and neoplasm.