It is mainly produced by activated Th2 cells and is associated with atopic dermatitis.12 IL-31 acts through a heterodimeric receptor consisting of IL-31 receptor A (IL-31Ra) and oncostatin M receptor, which are coexpressed on various immune cells such as monocytes, dendritic cells, and macrophages,12 13 as well as non-immune cells such as keratinocytes and epithelial cells.14 15 In IL-31Ra−/− mouse models, it has been shown that IL-31 may negatively regulate type 2 inflammation.16 However, the immunomodulatory role of IL-31 in cancer has not been elucidated. The gene discussed is IL31; the disease is cancer.