Comprises the proceedings of a symposium held at the Ciba Foundation, London, February 1988. Contains the latest research results on the inverse relationship between cell proliferation and differentiation and the nature of the genes involved. Included are the studies of cell fusion experiments, the introduction of single chromosomes into malignant cells, and the transfection of individual genes. Also reports on the role of certain oncogenes in normal development, lineage commitment, and tumorigenesis.