Table 2.

Radioligand binding competition ^a

Compound	% inhibition of [3H]vinblastine binding b
vincristine	65 ± 2
dolastatin 10	61 ± 1
colchicine	−11 ± 12
(−)-pironetin (1)	15 ± 4
(+)-pironetin (2)	3 ± 7
3	−6 ± 7
4	−3 ± 8

^aaverages ± SD (nM) from four independent experiments

^bat 5 μM test agent