Figure 4.

CDK1 phosphorylated Vgll4 during G₂/M-phase arrest. A, HeLa cells were treated with nocodazole and then fixed. Before the cells were stained with phospho-specific antibody against Ser-155/Thr-159 of Vgll4 (p-Vgll4 S155), they were preincubated with PBS (no peptide control) or non-phosphorylated (control) peptide or the phosphorylated peptide used for immunizing rabbits. CDK1 inhibitors RO3306 (5 μm) together with MG132 (25 μm) were added 2 h before the cells were fixed. B, HeLa cells were transfected with scramble siRNA or siRNAs targeting Vgll4. At 48 h post-transfection, cells were treated with nocodazole and then fixed for staining with phospho-Vgll4 Ser-155/Thr-159 (p-Vgll4 S155) antibodies. C and D, experiments were done similarly as in A and B with phospho-specific antibody against Ser-280 of Vgll4. White and yellow arrows mark some of the prometaphase cells and the interphase cells, respectively.