Effect of inhibition of CREB phosphorylation on MTOC polarization in Jurkat cells expressing Tax protein. Jurkat cells were infected with the Tax recombinant MVA at a multiplicity of infection = 10 pfu/cell. After overnight Tax expression, the Jurkat T cells were treated (or mock-treated) with 10 μM of STO-609 for 1 hour at 37°C, then mixed with uninfected and untreated Jurkat cells at a ratio of 1:1, and incubated at 37°C for 1 hour to allow cell-cell conjugate formation. The cells were fixed, and Tax protein, the microtubules, and the nucleus were stained by immunofluorescence using anti-Tax monoclonal antibody (Lt-4), anti–β-tubulin-CY3, and 4,6-diamidino-2-phenylindole (DAPI), respectively. In 2-cell conjugates (n = 50-100 in each experiment) formed between Tax⁺ and Tax⁻ cells, we scored the frequency of polarization of MTOC in the Tax⁺ cell to the cell-cell junction. The bars represent the mean plus or minus SE of 3 independent experiments.