Induction of apoptosis, cell cycle regulation, and in vitro inhibition of FLT3 and Aurora signaling by CCT241736 in MOLM-13 cells. (A) Immunoblotting analysis of cells treated with CCT241736 at the indicated concentrations for 24 and 48 hours using antibodies specific for cleaved PARP and survivin. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a loading control. (B) Cell cycle profile of MOLM-13 cells treated with FLT3 and Aurora kinase inhibitors or their combinations: CCT241736, MLN518, PHA-739358, or MLN518 + PHA-739358. MOLM-13 cells were treated for 72 hours with the compounds at the indicated concentrations approximating their viability IC₅₀ and 10 × IC₅₀, and they were fixed, stained, and analyzed by fluorescence-activated cell sorting (FACS). Y-axes represent FACS event counts (same scale for all histograms). The percentage of cells in sub-G₁, G₁, S, G₂, and 8N phases of the cell cycle are included. (C) After overnight incubation with 50 ng/mL nocodazole, MOLM-13 cells were treated with CCT241736, CCT137690, or MLN518 for 2.5 hours at the indicated concentrations. Cell lysates were prepared and analyzed for the expression of the indicated proteins by immunoblotting using specific antibodies. GAPDH was used as loading control.