A series of Vinca alkaloids were found to block polymerization of crude tubulin extracts of porcine brain in a dose-dependent manner. This appears to be a specific effect occurring at low concentrations of drug. The concentration of vinblastine that prevents polymerization by 50% was 4.3 × 10-7 mole/liter for a tubulin concentration of 3.0 mg/ml, and this concentration is consistent with levels achieved in vivo following routine pharmacological doses in humans.

1

This work was supported by NIH Grant CA 06973 and by the Eli Lilly Company.

This content is only available via PDF.