Effects of paclitaxel and 2d on microtubules in THP-1 cells. Cells were plated on coverslips and treated with 1 μM paclitaxel and 10 and 20 μM 2d for 48 h. After treatment, cells were fixed and processed for immunofluorescence/confocal microscopy using monoclonal α-tubulin antibody and secondary antibody conjugated with Alexa-488 (Invitrogen, Carlsbad, USA). 4′,6-diamidino-2-phenylindole (DAPI) was used for nuclear staining. The untreated cells show normal nuclear morphology and microtubules. Paclitaxel treatment causes the condensation and fragmentation of nuclei due to apoptosis (arrow) and also causes loss of microtubules (arrowhead). 2d treatment induces concentration-dependent increase in condensation and fragmentation of nuclei (arrow) due to apoptosis and also concentration-dependent loss of microtubules (arrowhead). Similar results were obtained in two separate experiments.