PDCD1 and neoplasm: This process involves the expression of immune inhibitory molecules (such as programmed cell death 1 (PD-1), PD-1 ligand1 (PD-L1), galectin-1, and FAS ligand (FASL)), loss of ability to upregulate CAMs, reduced adhesiveness, and insensitivity to inflammatory cytokines, thereby establishing a barrier to immune cell infiltration, in particular to activated cytotoxic CD8+ T cells—a condition known as tumor EC anergy [11,12,13,14,15,16].