ADORA2A and melanoma: In the presence of exogenous IFN‐γ and IL‐12 secreted by dendritic cells, inosine promotes Th1 differentiation by binding to adenosine 2A receptor (A2AR) on the surface of T cells and strongly improves the anticancer ability of Th1 cells in various tumor types which include melanoma, bladder cancer, and colorectal cancer.[52] However, in the absence of exogenous IFN‐γ, inosine inhibits the differentiation of Th1 and Th2 cells via A2AR.[53] Lipopolysaccharide (LPS) is the key component of the cell wall of gram‐negative bacteria and is considered a carcinogenic microbial metabolite.