Although it is unclear how PD-L1, which has a short cytoplasmic chain without an evident signaling motif, would be ligated under physiologic conditions to trigger tumor-specific activation of glycolytic metabolism, together these findings [16, 234] suggest that the PD-1: PD-L1 pathway may have significant implications not only on T cell anabolic metabolism but also on cancer cell metabolism and growth. This evidence concerns the gene PDCD1 and neoplasm.