Fig. 5.

MYPT1 siRNA increases the levels of phosphorylated MRLC, but does not impair furrowing and dephosphorylation during mitotic exit. a HeLa cells were treated with siRNAs directed against either a random sequence (control) or MYPT1 and after 48 h were fixed and stained to detect DNA (blue in the merged panels), tubulin, and di-phosphorylated MRLC pT18 pS19. DNA condensation and the shape and thickness of microtubule bundles at the intercellular bridge were used as criteria to stage telophase cells. Insets show a 3× magnification of the midbody. Scale bars, 10 µm. b Time course analysis of protein expression and phosphorylation during mitotic exit after MYPT1 depletion. HeLa cells were treated with siRNAs directed against either a random sequence (control) or MYPT1 and after 24 h synchronized by thymidine/nocodazole block. Cells were collected at the indicate time points after nocodazole (noc) release and proteins extracted and used in western blot analysis to identify the proteins and phospho-epitopes indicated to the right. The numbers on the left indicate the sizes of the molecular mass marker. Source data for Fig. 5b are provided as a Source Data file