Role of transgenic mice in identification and characterization of tumour suppressor genes.

Transgenic mice expressing various oncogenes have been generated and widely used to study their role in tumorigenesis. The development of targeted mutagenesis allows specific genes to be mutated in mouse embryonic stem cells, which can then be used to generate mice with a germline mutation in that gene. Embryonic stem cell technology has been used to reconstruct genetic lesions in tumour suppressor genes such as p53 and Rb1, originally identified from studies in humans. The tumour susceptibility phenotype of mutant mice has unveiled the tumour suppressor activity of specific genes that were not expected to have such a function. Transgenic and knock out mice will have an increasingly important role in the identification of novel tumour suppressor genes.