HLA-G and cancer: Innumerable reports describe methods to initiate, promote, or enhance immunotherapy of clinically detected cancer, notwithstanding the challenges, if not impossibility, of identification of tumor-specific, or associated antigens, the lack of tumor cell surface membrane expression of major histocompatibility complex (MHC) class I alpha and β2 microglobulin chains, and lack of expression or accessibility of Fas and other natural killer cell immune checkpoint molecules.