EM011 effectively kills CEM and CEM/VLB100 cells and induces G₂/M arrest. (A) Molecular structure of EM011. An acidic proton on position 9 of the isoquinoline ring system of the founding compound, noscapine, is substituted with a bromine group in EM011. (B) Plot shows the percentage of cell survival versus EM011 concentration. CEM and CEM/VLB100 cells were treated with gradient concentrations of EM011 for 48 hours, and the percentage of surviving cells at indicated drug concentrations was measured. (C) Quantitative representation of apoptotic index and mitotic index as a function of time of treatment with 10 μM EM011 in CEM and CEM/VLB100 cells. Panels D and E show the time effects of EM011 on the cell cycle progression of CEM and CEM/VLB100 cells, respectively. Cells were harvested for analysis at the indicated times, stained with PI, and analyzed by flow cytometry. The x-axis shows the intensity of PI fluorescence, which indicates cellular DNA content in different cell cycle phases. The y-axis represents the cell counts, and the z-axis shows the time of EM011 treatment. Results are representative of 3 experiments performed in triplicate.