Figure 9.

Cells expressing GFP-PakB-ΔPL and GFP-PakB-ΔC exhibit a defect in cytokinesis. (A) Average number of nuclei per cell was determined for JH10 cells (black bars), PakB-null cells (dark gray bars), and PakB-null cells expressing GFP-PakB-ΔC (light gray bars) or GFP-PakB-ΔPL (white bars) after 1, 3, and 6 d in suspension culture. (B) Time-lapse images of a dividing, adherent 2-h starved PakB-null cell expressing GFP-PakB-ΔPL. The cell was first imaged (0 s) after it had formed a long cytoplasmic bridge containing GFP-PakB-ΔPL. The white dotted lines indicate the outline of the dividing cell and two smaller cells (arrowheads) with GFP-PakB-ΔPL at the posterior that crawled over the cytoplasmic bridge. Cleavage of the first cytoplasmic bridge took more than 20 min to complete, at which time the cell had already started a second division that took more than 10 min to complete. After two divisions, one of the daughter cells retains the bulk of the GFP-PakB-ΔPL. Bar, 5 μm.