MICB (MHC Class I Polypeptide-Related Sequence B) is a gene that encodes a stress-induced protein involved in activating the immune system. It acts as a ligand for the NKG2D receptor found on natural killer (NK) cells and certain T cells, aiding the immune system in identifying and responding to infected or altered cells. MICB expression rises in response to cellular stress conditions, such as viral infections or tumor growth, enhancing immune surveillance and targeted destruction of affected cells.