Figure 5.

Microtubule destabilization by D-stathmins in vitro and in vivo. (A) Left, increasing amounts of D-stathmin-A were added to 18 μM tubulin, inhibiting the amount of microtubule polymerized at equilibrium as detected by turbidimetry at 350 nm. Right, linear dose-dependent decrease of the amount of microtubules polymerized at equilibrium in the presence of increasing amounts of D-stathmin-A, or -ΔC. (B) Immunocytochemical detection of overexpressed D-stathmin-A, -Ex2–5, -ΔC, and -ΔN myc-tagged proteins in HeLa cells with an anti-myc antiserum. Double labeling with anti-α-tubulin showed a destabilization of the microtubule network in the presence of all proteins but D-stathmin-ΔN. For each D-stathmin form, a field containing one nontransfected cell and one significant D-stathmin overexpressing cell (asterisk) is shown. A high magnification of the field is presented in order to visualize the microtubule network.