A vehicle includes a floor. A seat is supported by the floor. The seat includes a seatback. An actuator is fixed relative to the floor. The actuator is spaced from the seat along a vehicle-longitudinal axis. A track is fixed relative to the floor and is disposed between the seat and the actuator. The track is elongated along the vehicle-longitudinal axis. A slider is disposed in the track. The slider is slidable relative to the track by the actuator to a deployed position. A cable includes a first end fixed relative to the seatback and a second end fixed relative to the slider. The cable is under tension when the slider is in the deployed position.