Fig. 4. Disruption of actin filaments, but not of microtubules, alters Bpag1a/b2 localization. (A,B) Treatment with 200 nM cytochalasin D caused the aggregation of stress fibers in many of the C2C12 cells (B). In cells with a few remaining actin stress fibers, some A' staining (A) was still co-aligned with the fibers (arrow in A and B). In cells with no intact central stress fibers, A' staining was diffuse, and no filamentous pattern was ever observed. (C,D) Treatment with 500 nM nocodazole caused almost complete depolymerization of microtubules in the majority of the C2C12 cells (D), with most of the remaining microtubule staining existing at and close to the microtubule organizing centers (asterisks in D). A' staining in these cells (C) was not disrupted, as it was still observed in a filamentous pattern (arrow in C). Bar in D, 20 µm, and applies to all four images.