Tug-of-war for cytotoxicity: lytic granule movement at cytotoxic lymphocyte immune synapses. First, engagement of activating receptors induces dynein-dependent retrograde transport of lytic granules on microtubles toward the MTOC, followed by movement of the MTOC with clustered granules to the immune synapse. Second, a novel kinesin-1/Slp3/Rab27a complex mediates anterograde transport of lytic granules away from the MTOC and toward the plasma membrane, before final myosin-dependent exocytosis of granules at the immune synapse.