The cell cycle is the series of events that takes place in a cell leading to its division and duplication (replication). Regulation of the cell cycle involves processes crucial to the survival of a cell, including the detection and repair of genetic damage as well as the prevention of uncontrolled cell division. Two key classes of regulatory molecules, cyclins and cyclin-dependent kinases (CDKs), determine a cell's progress through the cell cycle.
Sources: [Wikipedia:Cell cycle](http://en.wikipedia.org/wiki/Cell_cycle), [KEGG](http://www.genome.ad.jp/kegg/pathway/hsa/hsa04110.html).