14. Polarization by microtubules
As we have seen, cell motility requires the development of a protruding front and a retracting rear, namely a polarisation of cell shape. Most cells are unable to polarise in the absence of a microtubules, pointing to a cross-talk between the microtubule and actin cytoskeletons for the development of polarity.
The loss of polarity of fibroblasts when microtubules are disassembled by drugs like nocodazole is illustrated in Fig. 14-1.
Figure 14-1. Video shows the effect of a microtubule inhibitor (nocodazole) on a goldfish fibroblast. Note the loss of polarisation of the cell following the depolymerisation of microtubules by this drug.
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Live cell imaging has provided compelling evidence about where the cross talk between microtubules and actin occurs, namely at the focal adhesions where the actin cytoskeleton is linked via transmembrane receptors to matrix ligands.