Tubulin (5 μM) was incubated with the different TPPP/p25 forms (10 μM) for 10 min at 37 °C in polymerization buffer. In another set of experiments, 10 μM paclitaxel-stabilized MTs was incubated with the different TPPP/p25 forms (10 μM) for 10 min at 37 °C in polymerization buffer. After centrifugation at 17000 g for 15 min at 37 °C, the pellet and the supernatant fractions were separated. The pellet fraction was washed and resuspended in buffer. Then the fractions containing 2-mercaptoethanol were analysed by SDS-PAGE, separated on a 13.5% gel and stained with Coomassie Brilliant Blue R-250.