Fig. 6.

Microtubules (MT) are indispensable for VEGF-induced cell elongation. a Confluent HUVECs immune labelled for VE-cadherin, α-tubulin and Phalloidin-TRITC after VEGF treatment for 24 h or PBS for control, as indicated. Nuclei are stained blue with DAPI. LSM demonstrates MT in control cells evenly distributed throughout the cells, while a few MT are aligned in parallel with JAAF (red arrows). VEGF-induced elongated cells display MT running parallel to the longitudinal cell axis together with stress fibres, and MT are enriched at the leading edge (white arrows; for dynamics compare supplementary Movie 10) (Scale bar: 20 µm). The cropped area displays an interrupted VE-cadherin pattern, MT enrichment, and stress fibres at the cell poles (arrowheads; for dynamics compare Supplementary Movies 10 and 11) (scale bar: 10 µm). b Confluent HUVEC cultures treated with 50 ng ml⁻¹ nocodazole for 4 h and subsequently labelled with VE-cadherin antibody and with Phallodin-TRITC for actin filaments. MT depolymerisation had less effect on the JAAF and VE-cadherin distribution (Scale bar: 20 µm). c–e Confluent HUVECs pre-treated with 50 ng ml⁻¹ nocodazole for 30 min and then treated with VEGF for another 18 h. c Phase-contrast microscopy revealed that nocodazole inhibited VEGF-induced cell elongation (scale bar: 80 µm). Quantification of (d) cell velocity and (e) cell elongation using Fiji software (100 cells were analysed at t = 0, 100 cells at t = 9 h, 81 cells at t = 18 h for nocodazole+VEGF treatment; and 100 cells were analysed at each time point for VEGF treatment, unpaired student’s t test). noco: nocodazole. Representative results from three independent experiments are shown. Error bars indicate ± SEM