CD8A and neoplasm: For example, major histocompatibility complex (MHC) class I polypeptide-related sequence A (MICA) and B (MICB) are stress-related proteins that are often upregulated on tumor cells but not healthy cells and can be recognized by NK group 2 member D (NKG2D) receptors expressed on CD8+ T cells and NK cells, as well as several other NK cell receptors [34,36].