2B4 is a human protein encoded by 2B4 gene. This gene encodes a cell surface receptor expressed on natural killer cells (NK cells) and some T cells, mediating non-major histocompatibility complex (MHC) restricted killing. The interaction between NK-cell and target cells via this receptor is thought to modulate NK-cell cytolytic activity. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. CD244 can also be expressed on non-lymphocytes such as eosinophils, mast cells and dendritic cells.