This cytokine belongs to the tumour necrosis factor (TNF) ligand family. It is a ligand for TNFRSF9, which is a costimulatory molecule in T lymphocytes. This cytokine and its receptor are involved in the antigen presentation process, and in the generation of cytotoxic T cells. This cytokine is also shown to be required for the optimal CD8 responses in CD8 T cells. This cytokine is found to be expressed in various carcinoma cell lines, and is thought to be involved in T cell-tumour cell inter