Mónica Gordón-Alonso, Esteban Veiga, Francisco Sánchez-MadridServicio de Inmunología, Hospital Universitario de la Princesa and Facultad de Medicina, Universidad Autónoma de Madrid, Diego de León, Madrid, SpainAbstract: Actins are a family of highly conserved proteins that play determinant roles in a variety of biological processes including: cell shape; migration; endocytosis/exocytosis; and adhesion. The dynamics of actin polymerization and depolymerization at specific cellular locations is tightly regulated and defines the cellular roles of actin. Here, we offer a perspective on the roles played by actin regulator molecules during the formation of the immunological synapse (IS) which is defined as the structure formed by the interaction between lymphocytes and antigen-presenting cells (APC). Proper actin dynamics at the IS are absolutely necessary for correct lymphocyte activation and alterations of such actin dynamics result in immune diseases.Keywords: actin, lymphocytes, immunological synapse, arp2/3, actin regulators