The role of tumour suppressor genes in apoptosis

Cancer is a multistep process, usually involving sequential changes in the cellular genotype and phenotype. One type of change which can potentially promote tumourigenesis is the abrogation of the normal cell death program (Umansky, 1982,- Arends andWyllie, 1991; Williams, 1991; Williams et al., 1992). Coupled with the acquisition of an ability to maintain unrestrained cell proliferation, illegitimate cell survival will conceivably give rise to highly malignant progeny. In fact, tumour progression is often accompanied by a reduced propensity to undergo cell death, as exemplified by the paradigms of rat hepatocellular carcinoma (Schulte-Hermann et at., 1990) and chicken bursal lymphoma (Neiman et al., 1991).