Hyperacetylation of MTs by drug treatment increases ER sliding but not TAC events. (A) COS-7 cells were fixed and immunofluorescently labeled with α-tubulin and acetylated α-tubulin after treatment with 125 nM TSA for 0, 30, 60, and 90 min. (B) COS-7 whole-cell lysate from cells treated for 0, 30, 60, and 90 min with 125 nM TSA were immunoblotted (IB) with antibodies to acetylated α-tubulin and α-tubulin. (C) Number of sliding events longer than 1 µm in a 10 × 10–µm region during 5-min period before and 30–35 and 60–65 min after treatment with 125 nM TSA (n = 4 different GFP–Sec61-β–expressing cells; see Videos 4 and 5). (D) Number of TAC events, as in C, in four different YFP-STIM1–expressing cells. (E) Graph of the curvature of ER sliding events (GFP–Sec61-β) from 60–90 min after 125 nM TSA treatment (n = 30) as compared with ER sliding curvature from Fig. 3 and the curvature of a representative population of MTs from a cell treated for 60 min with TSA (n = 35). Error bars show standard deviation. P-value was determined by unpaired t test: **, P < 0.001. (F) As in A, cells were treated for 0, 1, and 6 h with TSA. (G–I) As in A–C for cells treated with 10 µM tubacin. Bars, 10 µm.