During the last two decades has been possible to identify the molecular mechanisms that regulate the cell cycle and hence cell division. Accurate knowledge of how a healthy cell divides is useful to understand properly what has not worked in a tumor cell. In this context, the use of a model organism, such as Schizosaccharomyces pombe, has the advantage of a simple and easy genetic manipulation in the laboratory. Moreover, the underlying mechanisms that control the cell cycle are highly conserved through evolution and functioning of these processes appears to be very similar in all eukaryotic organisms. 1.2

Since the early eighties, it was shown that the onset of division cycle required the products of genes cdc2 and Cdc10. Of these, Cdc10 is part of a transcription factor known as CSM and whose activity is required for transcription of genes necessary to complete the S phase of cell cycle. At this time, and by proteomic approaches, experts are trying to figure out how this transcription factor regulates parallel cell cycle progression. In the context of this cycle, also want to know the mechanism for maintaining the quiescent phase in most cells of the body. Some MAP kinases seem to be decisive in the survival in stationary phase and, therefore, very important for chronological aging.

Finally, meiosis is the only exception to the normal cell cycle, as it has two nuclear divisions (phases of meiosis I and II), without interference by DNA synthesis. The cells of S. pombe require the activity of a meiosis-specific cyclin, REM1, for progress in the course of meiosis. Various research groups working today trying to characterize the role during these stages of meiosis and its transcriptional regulation. 3