Myeloid DAP12-associating lectin (MDL)-1, also designated CLEC5A, is a type II transmembrane protein belonging to the C-type lectin superfamily and expressed exclusively in monocytes and macrophages. MDL-1 contains a charged residue in the transmembrane region and this enables it to pair with DAP12 dimers. MDL-1's natural mammalian ligand is unknown, but MDL-1 is a receptor for Dengue virus CLEC5A is critical for dengue-virus-induced lethal disease (Chen et al 2008). Engagement with DAP12 has been shown to regulate osteoclastogenesis and myeloid cell-associated inflammatory responses (Bakker et al. 1999, Aoki et al. 2009, Inui et al 2009, Joyce-Shaikh et al. 2010, Cheung et al. 2011).