Tight control of the cell cycle in eukaryotic cells exists to control proliferation, differentiation or
apoptosis. These processes model and shape tissue and organ relationships in multicellular organisms. Two
biochemical processes, protein phosphorylation/dephosphorylation and ubiquitin-mediated degradation drive cell
cycle control. A multitude of pathways control cyclin-dependent kinase activities as the major event for cell cycle
progression. Differentiation and apoptosis have cell cycle withdraw in common, while cancer and degenerative
processes both show altered control of the cell cycle.
Keywords: Cell cycle, cancer, cyclins, apoptosis, check points, caspase, senescence, Bcl-2, cell differentiation,
cyclin-dependent kinase.