Cell cycle profile on DBTRG-05-MG GBM cells. Effect of the compound 1 on the cell cycle of DBTRG-05-MG cells. The cells were un-treated (Figure 5a), treated with 1 μM of the Ispinesib analog compound 1 for 24 hours (Figure 5b) after 24 h starvation. Nocodazole treatment was used as positive control (Figure 5c). Following incubation, the DNA of the cells was stained with propidium iodide and its content was analyzed by flow cytometry. Compound 1 induced a block of the cell cycle in G2/M phase. M1 (marker 1) represented G0/G1 phase; M2 (marker 2) represented the S phase; M3 (marker 3) represented G2/M phase.