Molecular aspects of DNA repair: Report of a workshop held at Noordwijkerhout (The Netherlands) 1–5 March 1987, Organized by P.H.M. Lohman, J.W.I.M. Simons, D. Bootsma, J.H.J. Hoeijmakers, B.A. Bridges, P. van de Putte and A.J. van der Eb