The invention relates to a radially compressible and expandable rotor (13, 13a, 13b) for a pump having at least one impeller blade (20, 22, 36, 36a, 36b, 36c, 36d, 36e, 36f, 36g, 37, 37a, 37b, 37c, 37d, 37e, 37f, 74, 88, 89, 90), wherein the impeller blade has an impeller blade body whose material is elastically deformable as well as at least one stiffening strut (25, 26, 27, 30, 31, 32, 52, 53, 57, 58, 62, 63, 67, 95) which is at least partially embedded in the material of the impeller blade body. The struts are designed suitably in size, shape and arrangement and are integrated in suitable hollow spaces of the impeller blade body for stabilizing the impeller blade. Elements with tensile strength can additionally be provided.