Moesin is a member of the ERM family which includes ezrin and radixin. ERM proteins, highly related members of the larger protein 4.1 superfamily, can exist in an active or inactive conformation. It seems that ERM proteins function as cross-linkers between plasma membranes and actin-based cytoskeletons. The sole Drosophila ERM protein, moesin, functions to promote cortical actin assembly and apical-basal polarity. As a result, cells lacking moesin lose epithelial characteristics and adopt invasive migratory behavior. It is localized to filopodia and other membranous protrusions that are important for cell-cell recognition and signaling and cell movement. Moesin contains 1 FERM domain and is expressed in all tissues and cultured cells studied. Moesin has been shown to interact with CD43, Neutrophil cytosolic factor 1, VCAM-1, Neutrophil cytosolic factor 4, ICAM3, and EZR.