LY290181, 2-amino-4-(3-pyridyl)-4H-naphtho (1, 2-b) pyran-3-carbonitrile, is a potent
antiproliferative compound that blocks cells in the G 2/M phase of the cell cycle by an
apparent action on microtubules. In the present work we found that LY290181 bound to
tubulin with high affinity (1 mol of LY290181 per mol of tubulin dimer; K a, 3.8× 10 5 M− 1)
and that it did not appear to bind at the colchicine or vinblastine-binding sites. LY290181
strongly stabilized microtubule dynamics as determined by video microscopy. It reduced the …