Cell Cycle | GeneTex

The cell cycle is an ordered set of events by which cells undertake growth and division into two daughter cells. In eukaryotes, the cell cycle is described by five phases: G0, G1, S, G2, and M. In G0 phase, cells have entered a quiescent state or are not dividing. During G1 period, the cells grow and accumulate nutrients for the subsequent S phase, where DNA replication occurs. The gap between S and M phases is termed G2 period, during which the cells continue to grow and prepare for mitosis that occurs in M phase. All these processes are elaborately controlled to ensure proper cell development and renewal. The key molecules that program cell cycle are cyclins and cyclin-dependent kinases (CDKs), whereas inhibitors that prevent improper cell division are two families of genes, the Cip / Kip family and the INK4 family. Notably, these inhibitor genes are also termed tumor suppressor genes as they are instrumental in the prevention of tumor formation.