exit from mitosis induced by a calcium transient the relation to the mpf and insp3 dynamics cells divide only after passing through a control point in late g1 this passage is followed by the accumulation of the mitotic cyclin which binds to p34cdc2 allowing for the subsequent phosphorylation and dephosphorylation of the latter protein it is the active mpf ie the phosphorylated mitotic cyclinp34cdc2 kinase complex that triggers entry into mitosis mpf becomes increasingly active as the cell forwards to anaphase when a sudden increase in insp3 takes place this in turn induces a large ca2 release in cytosol from internal calcium stores and a calciumdependent positive feedback control on insp3induced calcium release enhances the effect on insp3mediated ca2 transient meanwhile empty calcium stores signal to plasma membrane for a constant calcium influx at high insp3 levels the cytosolic calcium excess is assumed to activate the camkll holloenzyme which involves the production of the ubiquitination complex necessary for cyclin degradation and mpf inactivation accordingly a mathematical model was proposed by means of an eightdimensional dynamical system that yields the time dependence of the main cellular quantities in a picture of the mitosis specific events