Illustration of the proposed compartment models. Panel A illustrates a compartment model where the drug is assumed to induce cell cycle arrest with halving time and for cells in cell cycle arrest the death rate is assumed exponential with halving time . Panel B illustrates a simplified compartment model in which the drug is assumed to induce cell death with halving time . In both models the cell line grows with doubling time T0. Panel C illustrates growth curves according to Model B for a cell line with T0 = 60 hours and N0 = 30,000 cells treated with three different concentrations of a potent drug. The concentrations correspond to the summary statistics G I50 = c1, TGI =c2, and LC48 = c3.