This volume is based on the proceedings of a NATOjFEBSjGulbenkian Foundation sponsored Summer School held in September 1984 in Sintra Estoril, Portugal. Given the accelerated growth of knowledge in the field of cell transformation, it seemed timely to hold a summer school to discuss current developments in this area of biology as well as to evaluate emerging technology. The first article in this volume gives an evaluation of the various cellular systems to study neoplasia. Their properties as well as advantages and disadvantages are dis cussed. The second section deals with the role of...