STING1 and Carcinoma, Lewis Lung: In contrast, another study showed that STING-triggered indoleamine 2,3 dioxygenase (IDO) activity in the tumor microenvironment (TME) promotes Lewis lung carcinoma (LLC) growth and that STING deficiency led to increased CD8+ T cell-mediated tumor cell killing indicating that STING decreases CD8+ T cell effector functions in this context [128].