Estimation of cell cycle parameters by the cumulative method.

Cell cycle parameters exhibit one of the characters of tumor cells. The cumulative method for the estimation of the parameters was analysed and evaluated, considering variations of the phase duration. The following procedure was proposed for the accurate estimation: The cell cycle time and the duration of G2 phase are estimated from the accumulation of mitotic cells and labeled mitotic cells, respectively, by the simultaneous administration of an inhibitor of cell division and a labeled DNA precursor. The duration of S phase is calculated with the labeling index using an equation. The duration of G1 phase is obtained by subtraction from the cell cycle time.