I think taxol is an inhibitor of DNA replication.
It is very important since it has an anti-tumoral
effect (since kills fast-dividing cells).
There was a Nature article on its synthesis
(which is probably one of the most sought-after
results in organic chemistry) a while ago, about 3-4 months.
In the issue there was also a description of the effects
and the economic importance of the compound.
Hope this helps