Identification and characterisation of cancer genes

Cancer genes have been subdivided into oncogenes and tumour suppressors though the distinction is not entirely valid. In many cases their effects can be demonstrated by induction or reversal of a transformed phenotype following transfection into a suitable host cell but full characterisation requires isolation by positional cloning and analysis of function at the molecular level. Almost all have been ascribed some function within the complex pathways of signal generation, receipt and response that regulate cell growth and differentiation. However, few, if any, tumours result from just a single mutation and the key to a real understanding of the molecular basis of malignancy must be studies, currently in their infancy, of interactions between the various genes implicated in the initiation and progression of cancer.