PDCD1 and cancer: Furthermore, activation of JAK2/ STAT3, PI3K/Akt/mTOR, and MAPK/ERK pathways, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and HIF-1α can regulates the programmed cell death 1 (PD-1)/programmed cell death-ligand (PD-L1/2) immune signaling pathway in various types of cancer cells 9.