They demonstrate that PD-1 expressed on tumor cells increases the level of phosphorylation of S6 (pS6), mTOR effector molecules, and eukaryotic initiation factor 4E (eIF4E), which are responsible for cellular proliferation (Schatton et al., 2010; Kleffel et al., 2015; Li et al., 2017). This evidence concerns the gene PDCD1 and neoplasm.