Components of the dynactin complex stabilize microtubules. (A) Diagram of the dynactin complex including the Arp1 filament and shoulder and arm domains to include Jnm1 and Nip100. Colored regions are tested in our analysis. (B) Median microtubule length measured in pre-anaphase cells (μm). Diagram shows cellular location for bud (B)-directed microtubules and mother (M)-directed microtubules. WT, n = 166 cells; nip100Δ, n = 192 cells; dyn1Δ nip100Δ, n = 152 cells; nip100ΔCAP-Gly, n = 313 cells; jnm1Δ, n = 174 cells; arp1Δ, n = 128 cells. Error bars are 95% c.i. Asterisks denote a significant difference from WT. *, P < 0.05; **, P < 0.005; ***, P < 0.0001; determined by t test.