Diethylstilboestrol: the binding and effects of diethylstilboestrol upon the polymerisation and depolymerisation of purified microtubule protein in vitro.

Diethylstilboestrol (DES) was shown to bind to purified microtubule (MT) protein and inhibit the binding of colchicine. The polymerisation and depolymerisation characteristics of MT protein in vitro were examined using spectrophotometry and electron microscopy. At high doses of DES the polymerisation of intact microtubules was inhibited, whilst at lower doses enhanced microtubule formation was observed. The lower doses of DES inhibit the depolymerisation of intact microtubules.