IL6 and neoplasm: The stimuli produced by tumor cells and stromal cells, such as fibroblasts, in the tumor microenvironment can activate fibroblasts and contain, among others, interleukin-1, interleukin-6 (IL-6), bone morphogenetic protein, sonic hedgehog, reactive oxygen species, transforming growth factor-β (TGF-β), platelet-derived growth factor, and tumor necrosis factor [17].