Inhibits osteoclast formation. Receptor for KLRB1F. Enhances T-cell activation. Plays a role in splenocyte activation, T-cell responses and IL-2 production. Detected in osteoblasts, growth plate chondrocytes and skeletal muscle overlying the bone (at protein level). Detected in spleen, B-cells, dendritic cells, thymus, and in IL2-activated natural killer cells. Up-regulated in CD4(+) T-cells upon stimulation with CD3-ligands. Up-regulated in cultured calvarial osteoblasts by 1,25-dihydroxyvitamin D3. Constitutively expressed in cultured bone marrow cells during osteoclast formation.