Importantly, we discovered that cytoplasmic cyclin B1-Cdk1 activity can be maintained even when cyclin B1 translocates to the nucleus in prophase.     ///    "By quantifying both dephosphorylation of Cdk1 and phosphorylation of the Cdk1 target anaphase-promoting complex/cyclosome 3, we disclose how cyclin B1-Cdk1 continues to be activated after centrosome separation. "    ///    "These experimental data are fitted into a model describing cyclin B1-Cdk1 activation in human cells, revealing a striking resemblance to a bistable circuit. "    ///    "In line with the observed kinetics, cyclin B1-Cdk1 levels required to enter mitosis are lower than the amount of cyclin B1-Cdk1 needed for mitotic progression. "    ///    " Activation of cyclin B1-cyclin-dependent kinase 1 (Cdk1), triggered by a positive feedback loop at the end of G2, is the key event that initiates mitotic entry. "    ///    We propose that gradually increasing cyclin B1-Cdk1 activity after centrosome separation is critical to coordinate mitotic progression..     ///    We use a novel approach to determine the temporal development of cyclin B1-Cdk1 activity in single cells.     ///    Cyclin B1-Cdk1 activation continues after centrosome separation to control mitotic progression.. 