Tubastatin A and TSA increased the microtubule acetylation level. Effects of tubastatin A (A and B) and TSA (C and D) on microtubules and microtubule acetylation level are shown. A and C, MCF-7 cells were treated with different concentrations of tubastatin A (A) or of TSA (C) for 24 h and processed for immunostaining with antibodies against α-tubulin (green) and acetylated tubulin (red). Scale bars, 10 μm. B and D, MCF-7 cells were treated with different concentrations of tubastatin A (B) or of TSA (D) for 24 h. Polymeric fractions of tubulin were isolated, processed for Western blotting, and were probed for α-tubulin and acetylated tubulin.