Effect of N-BPs on microtubule structure. (a) Effect of N-BP treatment on TBCB expression levels. Western blotting (WB) analysis showing the protein levels of TBCB after stimulation with 10-4M ALE, RIS and IBA for 24, 48 and 72 h, respectively. The signal given by total actin was used as a loading control (Ctrl). (b) N-BPs disrupt microtubule cytoskeleton organization. Ultrastructural pictures of MCF-7 cells under different conditions. Left panels: presence of a tightly packed bundle of microtubules arranged in a parallel way within a lamellipodial protrusion, under basal conditions (original magnifications: × 35,000 (top); × 45,000 (bottom)). Top right panel: irregular microtubular organization after N-BP treatment (10-4 M, 72 h; original magnification × 35,000). Bottom right panel: anti-tubulin immunogold labeling of filamentous structures after N-BP treatment (original magnification × 22,000).