Recent genetic and biochemical studies have provided new insights into the
molecular basis of centrosome-mediated microtubule nucleation. In addition,
molecules and mechanisms involved in microtubule severing and stabilizatio
n at the centrosome, assembly of proteins onto centrosomes and regulation o
f centrosome duplication and separation are being defined. Characterization
of centrosome function, together with studies implicating centrosomes in t
umorigenesis and demonstrating that centrosomes are highly organized, are b
eginning to bring into focus an organelle once viewed as an 'amorphous clou
d'.