Clone REA999 recognizes the mouse antigen TIM-4, which is also known as T cell immunoglobulin and mucin domain-containing protein 4 or spleen, mucin-containing, knockout of lymphotoxin protein (SMUCKLER). TIM-4 is a member of the TIM gene family, which is involved in a variety of immunity related processes including T cell proliferation and survival, tissue inflammation, and atopy. In mice, eight TIM genes encode the proteins TIM-1 to TIM-8, whereas only three TIM genes are found in humans encoding TIM-1, TIM-3, and TIM-4. In spleen, TIM-4 is expressed on antigen presenting cells such as lymphoid and myeloid dendritic cells and macrophages but not by T or B lymphocytes.