FIGURE 5.

The effects of honokiol on tubulin. (A) To evaluate the effects of cisplatin and HNK on the polymerization of tubulin, maximum de-polymerization was achieved by incubation of cells in 10 μM of colchicine for 24 h. Tubulin bundles were visualized and marked with red arrowheads. When cells were treated with cisplatin, no change on tubulin bundle was observed; however, when cells were treated with HNK, significant 1.8-fold increase of tubulin bundle was measured. (B,B1) Control cells showed complexity of tubulin network with apparent microtubule organization centers (marked in red arrowheads). (B2) Cells recovered in medium containing 10 μM colchicine showed punctate tubulin signal in the cytosol, and (B3) when cells were allowed to recover (for 4 h) in culture medium containing 10% FBS (complete culture medium), tubulin bundle as well as microtubule organizing center can be observed again. (B4) When cells recovered in the presence of 10 μM cisplatin, punctate tubulin signals were observed. However, when HNK was present either alone (B5) or was co-present in the recovery medium (B6), elongated tubulin and microtubule organizing center (marked with red arrowheads) can be observed. Images presented were representative images, and at least 20 images from each group were taken randomly and assessed. a–c indicated significant (p < 0.05) difference between groups. Lat. B, latrunculin B.