IL21 and digestive system cancer: IL-23 is secreted by tumor-associated immune cells and promotes IL-17 production38 along with IL-21, IL-6, and IL-1 via transcription factors such as NFATc1, ROR, and STAT3.16 Tang et al39 showed that IL-23 is required for the production of IL-17 by γδ T cells, and Richter et al40 affirmed its significant role during colon carcinogenesis.