Conversely, co-stimulatory molecules like inducible T cell co-stimulator (ICOS), glucocorticoid-induced TNFR-related protein (GITR), and OX40, expressed on various immune (e.g., T cells, Tregs, and NK cells) and non-immune cells (e.g., endothelial cells), are being evaluated for their potential in cancer immunotherapy. Here, ICOS is linked to cancer.