Microtubules are involved in IL-1β secretion. (A) Monocytes were stimulated for 4 hours with LPS in the absence (lanes 1 and 5) or presence of 1 μM cytochalasin D (cyD; lane 3), 1 and 10 μM nocodazole (noc; lanes 2, 6, and 7) or 10, 20, and 40 μM taxol (lanes 4, 8-10). At the end of the 4-hour incubation, supernatants were analyzed as such (lanes 1-4) or 1 mM ATP was added for 15 minutes (+ATP; lanes 5-10) before Western blot analysis for the presence of IL-1β. (B) Monocytes treated as in panel A were fixed, permeabilized, and stained with anti-tubulin-α ()or anti-acetyl-tubulin-α (□) and analyzed by cytofluorimetry. Data are expressed as mean fluorescence intensity. For each panel, one representative experiment of at least 5 performed is shown. (C) Monocytes were activated 4 hours with LPS and 1 μM cytochalasin D in the absence (-; lane 1) or presence of HC-toxin (1 μM, lane 2), ITF2357 (50 nM, lane 3), SAHA (0.5 μM, lane 4), AACOCF3 (AA; 40 μM, lane 5), BEL (100 μM, lane 6), EGTA (5 mM, lane 7). At the end of the 4-hour incubation, supernatants were analyzed by Western blot for the presence of IL-1β.