The Immune Synapse (IS) is a specialized structure formed at the contact area between T lymphocytes and antigen-presenting cells (APC), essential for the adaptive immune response. Proper T cell activation requires its polarization towards the APC, which is highly dependent on the tubulin cytoskeleton. Microtubule associated protein-4 (MAP4) is a microtubule (MT)-stabilizing protein that controls MTs in physiological processes such as cell division, migration, vesicular transport or primary cilia formation. In this study, we have assessed the role of MAP4 in T cell activation. MAP4 decorates the pericentrosomal area and MTs of the T cell, and it is involved in MT detyrosination and stable assembly in response to T cell activation. Also, MAP4 prompts the timely translocation of the microtubule organization center (MTOC) towards the IS and the dynamics of signaling nanovesicles that sustains T cell activation. However, MAP4 acts as a negative regulator of other T cell activation-related signals, including DAG production and IL2 secretion. Our data indicate that MAP4 acts as a checkpoint molecule that balances positive and negative hallmarks of T cell activation.