Do all daughter cells enter the "indeterminate" ("A") state of the cell cycle? Analysis of stathmokinetic experiments on L1210 cells.

The results of ten different stathmokinetic experiments on L1210 cells are analyzed to determine whether all the postmitotic cells enter the exponential AG1 compartment of the cell cycle characterized by exponentially distributed transit times. The analysis is based on a mathematical model coherent with the generalized A-B-transition hypothesis. An original fitting procedure is introduced to estimate the fraction of cells entering AG1 as well as other parameters of the cell cycle. Results of the analysis suggest that either all or nearly all postmitotic cells enter G1A. The results are discussed with respect to the validity of the A-B-transition hypothesis of the "probabilistic" model of the cell cycle. Some systematically occurring discrepancies that do not conform with generally accepted cell cycle models are apparent from the analysis of this data.