HDAC6-dependent deacetylation of α-tubulin induced by TGF- β1. A, serum-starved A549 cells were exposed to TGF-β1 (2.5 ng/ml) for the indicated durations, and protein levels of α-tubulin and acetylated α-tubulin were examined by immunoblots at 48 h after exposure. B, serum-starved A549 cells were exposed to increasing doses of TGF-β1 for 48 h, and protein levels of α-tubulin and acetylated α-tubulin were examined as in A. C, culture conditions were similar to those in A, except that the protein levels of α-SMA, α-tubulin, and acetylated α-tubulin were examined in the primary cultures of human lung fibroblasts and arterial endothelial cells exposed to TGF-β1 (3 ng/ml) for 48 h. D, serum-starved A549 cells were exposed to TGF-β1 (2.5 ng/ml) with either tubacin or niltubacin (5 μm) for 48 h. The protein levels of α-tubulin and acetylated α-tubulin were examined as in A. E, serum-starved A549 cell variants were exposed to TGF-β1 (2.5 ng/ml) for 48 h, and the protein levels ofα-tubulin, acetylatedα-tubulin, and HDAC6 were examined as in A. α-Tubulin-ac, acetylated α-tubulin. HPAEC, human pulmonary arterial endothelial cells. HLF, human lung fibroblasts. T and N, tubacin and niltubacin, respectively. KD, A549 cells that express HDAC6-targeting siRNA. pS, control A549 cells. Results are representative of at least two independent experiments.