Although loss of p25 has no apparent effect on the Arp1 filament, the A. nidulans p25 is indeed a component of the dynactin complex. (A) Western blots showing Arp1 proteins pulled down by the S-tagged p150 in wild-type and Δp25 extracts. (B) A quantitative analysis of the Western results on p150–Arp1 interaction in the Δp25 mutant. All the values were relative to wild-type values, which were set as 1. Mean and standard deviation values (error bars) were based on results from three independent experiments. At P = 0.05, there is no significant difference between wild-type and Δp25 values. (C) p25-GFP forms benomyl-sensitive comet-like structures, consistent with being a component of the dynactin complex. For treatment with benomyl to depolymerize microtubules, 2.4 µg/ml of benomyl was used to treat the cells for 20 min. Bars, 5 µm. (D) A Western blot showing that the p25-GFP protein level was dramatically decreased in Arp11-depleted cells but not in p62-depleted cells. (E) S-tagged p150 was able to pull down p25-GFP from both the wild type and the p62-depleted extracts.