The primary function of PD-1 is in peripheral tissue where T-cells encounter immunosuppressive ligands PD-L1 (also known as B7-H1 or CD274) and PD-L2 (also referred to as B7-DC or CD273) which are expressed by tumor and/or stromal cells (Dong et al., 1999; Menzies et al., 2012; Topalian et al., 2012). The gene discussed is PDCD1LG2; the disease is neoplasm.