EMR1 (EGF-like module containing mucin-like hormone receptor 1), also known as Adhesion G protein-coupled receptor E1 (ADGRE1), is a surface receptor with seven transmembrane segments that belongs to the EGF-7-transmembrane family of G protein-coupled receptors (PMID: 14647991, 7601460). EMR1 expression is restricted to eosinophilic granulocytes, where expression is overlapping with the eotaxin receptor CCR3 and the immunoglobulin-like lectin Siglec-8. Absence on other leukocytes, including basophils, implies that EMR1 is a highly specific marker for eosinophils in humans and may be used as a novel therapeutic target for eosinophilic disorders(PMID: 17823986, 24530099). F4/80, the murine homolog of EMR1, is a marker of murine macrophage. The apparent molecular weigh of F4/80 is 160 kDa, which is lager than the calculated molecular weight due to post-translational modifications (PMID: 7308288; 8647179).