CD274 and neoplasm: Though these mechanisms can aid in the clearance of tumors, tumor-infiltrating lymphocytes often display upregulation of inhibitory markers, such as PD-1 and CTLA-4, which bind PD-L1 and CD80/CD86, respectively; these can halt anti-tumoral effector functions and result in reduced effector cytokine production (Ahmadzadeh et al., 2009).