Dynein movement of microtubules.
<P>
<lI> The  dynein  arms  of  one  microtubule  doublet grip the adjacent
doublet, push it up, release, and then grip again.
<lI> The  doublet  do  not  slide  far  past  each other since they are
restrained by cross-linking proteins, so they bend.
<lI> Repeated bending yields a wavelike motion.