Protein 4.1R stabilizes the red-blood-cell membrane by anchoring integral membrane proteins to the spectrin-actin skeleton below. It is also present in nonerythroid cells at various subcellular locations. Isabel Correas and co-workers now reveal that here it regulates a very different component of the cytoskeleton: microtubules (see p. 6197). They find that expressing 4.1R in fibroblasts alters interphase microtubule architecture rather than the actin cytoskeleton. In addition, it disrupts centrosomes, causing the microtubule motor dynein to become displaced from these organelles. The authors then use confocal microscopy and western blotting to demonstrate that endogenous 4.1R can be identified in isolated centrosomes. Moreover, they show recombinant 4.1R localizes to the centre of microtubule asters produced in vitro and can promote their assembly. Correas and co-workers conclude that 4.1R plays a role at centrosomes in maintenance of the radial microtubule arrays that these organelles control. One possibility is that it also has...

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