Appropriate levels of ternary complex components are necessary for proper spindle positioning in HeLa cells. (A–D) Distribution of metaphase spindle angles with respect to the fibronectin substratum in cells transfected with YFP (A), Gαi₁-YFP (B), YFP-LGN (C), or Gαi₁-Δmyr-YFP (D). A minimum of 40 cells was analyzed for each condition, and the significance was compared with control cells (YFP) using a two-tailed Student’s t test; in all three experimental conditions, P < 0.001. (E–H) HeLa cells transfected for 36 h with YFP (E), Gαi₁-YFP (F), YFP-LGN (G), or Gαi₁-Δmyr-YFP (H) and stained for the dynactin subunit p150^Glued. Arrows point to cortical p150^Glued. Over 95% of cells transfected with Gαi₁-YFP (F) or YFP-LGN (G) exhibited more extensive p150^Glued signal at the cell cortex than those transfected with YFP alone (E; n > 100 in each condition, except for H, in which n = 32).