The epidermal growth factor (EGF)-TM7 family constitutes a group of class B G-protein coupled receptors, which includes CD97, EMR1 (EGF-like molecule containing mucin-like hormone receptor 1, designated F4/80 in mouse), EMR2, EMR3, FIRE, and ETL (1–3). These family members are characterized by an extended extracellular region with several N-terminal EGF domains, and are predominantly expressed on cells of the immune system (1–3). The EGF-TM7 protein family are encoded by a gene cluster on h