Inhibition of dynein dephosphorylation reduces poleward streaming of dynein. (A) NRK2 cells stained for DAPI (1 and 5), tubulin (2 and 6), and total dynein (3 and 7) at metaphase reveal a loss of the PT89 signal at kinetochores, but it is present at spindle poles and along spindle fibers in controls (1–4). Dynein is still detected at kinetochores but is less prominent at spindle poles and along spindle fibers in cells treated with taxol (5–8). (B) Live cell analysis of metaphase cells expressing low levels of GFP-p50(dynamitin) under control conditions (1–4) or after treatment with taxol (5–8). Particles of GFP-p50(dynamitin) labeling (white arrows) can be seen moving poleward from kinetochores (red arrows) and label spindle fibers in controls (1–4; Video 3, available). After taxol treatment (5–8; Video 4), GFP-p50(dynamitin) labeling is intense at kinetochores but does not exhibit movement or label spindle fibers. (C) Line plot of GFP-p50(dynamitin) intensities for control and taxol-treated cells. Intensity measurements were collected for five kinetochores, and mean intensity is plotted with SD (error bars). Bars, 5 μm.