Dynein pathway function is enhanced in Tub1-only versus Tub3-only cells with epothilone-stabilized microtubules. Drug-sensitized cells (pdr1Δ pdr3Δ) in mid-log phase were arrested in HU for 90 min, followed by addition of 10 µM epothilone B (EpoB) for another 60 min (a–e). Parameters of Dynein-mediated sliding activity in epothilone B– or mock (DMSO)-treated cells of the indicated genotypes. Note: Dynein deletion cells (far right; dyn1Δ) are not drug sensitized and were not treated with epothilone B or DMSO. Absence of a bar indicates no events were observed in dyn1Δ cells. (a) Maximum length attained by astral microtubules during Dynein-mediated spindle sliding. Maximum length during sliding is generally comparable in mock and epothilone B–treated cells. (b) Percentage of cells that display Dynein-mediated spindle sliding movements. (c) Frequency of Dynein-mediated spindle sliding movements in individual cells. (d) Frequency of astral microtubule contact with the bud cell cortex in individual cells. (e) Distance of spindle translocation by Dynein-mediated sliding events. For panels a–e, graphs show mean ± SEM from two trials; 30–40 cells were analyzed per genotype for each treatment condition; for Dynein-mediated sliding events, in Tub1-only epothilone B, n = 12 and 43; WT-Tub1 epothilone B, n = 13 and 12; WT-Tub3 epothilone B, n = 5 and 14; Tub3-only epothilone B, n = 6 and 16; Tub1-only DMSO, n = 27 and 19; WT-Tub1 DMSO, n = 8 and 13; WT-Tub3 DMSO, n = 12 and 10; and Tub3-only DMSO, n = 6 and 12. For dyn1Δ cells, n = 0 and 0 for observed sliding events. n.s., not significant; *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001 by unpaired, two-tailed Student’s t test. MT, microtubule.