GSK-3 inhibitors delay mitotic entry and exit. HeLa cells were synchronised at G1/S then released into drug-free medium or medium containing either SB-415286 or nocodazole. At the time points indicated the cells, were harvested and analysed by flow cytometry to determine DNA content and mitotic index. (A) DNA content histograms showing that SB-415286 delays cell division. (B) Graph plotting the mitotic index, as determined by MPM-2 reactivity, showing that mitotic progression is delayed in SB-415286 treated cells.