Interestingly, IL-17 also promotes tumor progression through inducing terminal exhausted CD8+ T cell differentiation.503 Apart from immune cells, IL-17 increases vascular endothelial cells number in gastric cancer,504 triggers CAFs to produce myeloid cell stimulatory factor G-CSF,505 and promotes skin tumor formation by stimulating keratinocyte proliferation.506 Furthermore, Th17 cells secrete high level of IL-22 which enhances the tumor growth and metastasis in human colon cancer.507,508. This evidence concerns the gene IL17A and skin neoplasm.