DUB expression and ubiquitination may regulate IL-2 signaling.

(A) Constitutive expression of DUB-2 in HTLV-1–transformed T cells. Ba/F3β, Molt-4β, and MT-2 cells were stimulated with IL-2 for 4 hours and lysates were immunoprecipitated with antisera to DUB,12 followed by Western blotting with the same antibody. (B) The proteasome inhibitor MG132 stabilizes IL-2–induced tyrosine phosphorylation of IL-2Rβ and STAT5b. KIT-225 cells were pretreated with 5 μM MG132 or control DMSO and stimulated with IL-2 for 20 minutes. The cells were then incubated in cytokine-free media containing MG132 or DMSO for the indicated times. Cells lysates were immunoprecipitated with anti–IL-2Rβ or anti-STAT5b, and immunoblotted with antiphosphotyrosine (pY), IL-2Rβ, or STAT5b antisera as indicated.