[Cell cycle control, genetic instability and cancer].

During the past years the elucidation of cell cycle regulation has revolutionized our understanding of cancer development. Many new genes have been identified which promote genetic instability when mutated. They encode cyclins, inhibitors of cyclin-dependent kinases (CDKs) or other cell cycle regulators. The regulation of the CDK activities in different phases of the cell cycle controls the correct process of DNA synthesis and replication. Complex signal transduction systems, so-called checkpoints, regulate growth arrest, DNA repair and programmed cell death (apoptosis) and thereby prevent the formation of tumour cells. An overview is presented on the molecular mechanisms of cell cycle control and their significance for genetic stability. The functions of proto-oncogenes (e.g., c-myc) and tumour-suppressor genes (e.g., p53) in this context is described. In particular, recent advances in the understanding of skin carcinogenesis, the role of UV radiation and cancer therapy are discussed.