Roll-over protection system with a deformable portion

The structure has a roll-over part, supported on a vehicle body part during a roll-over, with a support element on which the vehicle rolls-over. The strut-shaped support element (8) is arranged as a defined deformation part for a limited defined deformation in load direction acc. to a defined power-distance diagram, to reduce energy. The roll-over part (2), an associated guide part (1), its fastening, and a retraction blocking device (3,6), form a rigid system. The support element is a hollow profiled part, and is fitted to the roll-over part.