B2M and neoplasm: The HLA-A protein, which is a single-pass transmembrane protein, represents one of three major subclasses of HLA class I cell surface receptors, which form a complex with B2 M/beta2 microglobulin that binds viral and tumor-derived peptides for presentation to HLA-A–restricted CD8+ T cells to guide the acquired immune response to eliminate aberrant cells [38–40].