Is taxol a surrogate for a universal regulator of mitosis?

Taxol is well recognized as an antitumor agent and a biochemical tool for studies of microtubules. A proposal is made that taxol is a surrogate for a key endogenous regulator of microtubules, which has the particular function of stabilizing the mitotic spindle. This proposal is based on evidence from the breadth of taxol activity across organisms, data supporting a highly conserved binding site for taxol, low-dose effects of taxol targeting the mitotic spindle, the restriction of the binding site to a highly conserved segment of B-tubulin, data on the biosynthesis and distribution of taxol, and the recent discovery of an anti-idiotype antibody with taxol-like activity.