Cell cycle, the ordered sequence of events that occur in a cell in preparation for cell division. The cell cycle is a four-stage process in which the cell increases in size (gap 1, or G1, stage), copies its DNA(synthesis, or S, stage), prepares to divide (gap 2, or G2, stage), and divides (mitosis, or M, stage). The stages G1, S, and G2 make up interphase, which accounts for the span between cell divisions. On the basis of the stimulatory and inhibitory messages a cell receives, it “decides” whether or not it should enter the cell cycle and divide. The M Phase represent the phase when the actual cell division or mitosis occurs and the interphase represent the phase between two successive M phase . It is significant to note that in the 24 hours average duration of cell cycle of a human cell, cell division proper lasts for only about an hour.