Significant progress, achieved in the last two decades, in understanding processes that enable cancer to grow and metastasize freely, while evading the immune response of the host, has largely been associated with exploring pathways controlling the apoptosis (e.g., with apoptosis inhibitor proteins, AIP) and the immune checkpoints (e.g., with programmed death protein 1, PD-1). Here, PDCD1 is linked to cancer.