267/Dt treatment of LCC6, LCC6Her2, MCF-7, and MCF-7Her2 causes disruption of normal F-actin cytoarchitecture and abnormal nuclear morphology. LCC6, LCC6Her2, MCF-7, and MCF-7Her2 were treated for eight hours with 267 (42 μM), Dt (1 nM) or the combination of 267 and Dt. Subsequently, cells were fixed using paraformaldehyde, permeabilized, and stained for nuclear material using Hoechst and F-actin using Texas red conjugated phalloidin. Representative photomicrographs of (a to d) untreated cells or cells treated with (e to h) QLT0267 (267), (i to l) docetaxel (Dt) and (m to p) the combination of 267/Dt are shown, where blue represents the nucleus and red the F-actin microfilaments. Combination treatment resulted in a distinct decrease in total F-actin staining, a change in actin organization, the appearance of apoptotic nuclear bodies (white arrows), as well as metaphase chromosomes suggestive of a cell cycle block in these cells.