Down-regulation of Stat5A in the cytoplasm and the nucleus. (A) No effect of the nuclear export inhibitor LMB on the down-regulation of active or total Stat5A proteins in the nucleus. 32D (EpoR wt) cells were starved overnight and pretreated with or without LMB, followed by stimulation with IL-3. After removal of the cytokine, cytoplasmic and nuclear extracts were prepared at the indicated time points and subjected to Western blot analyses with anti–phospho-Stat5 (α-pStat5), anti-Stat5A (α-Stat5A), or anti–nuclear protein YY1 (α-YY1) antibodies. (B) LMB treatment resulting in nuclear accumulation of p53. As a control, cytoplasmic and nuclear extracts from Hela cells treated with LMB were subjected to Western blot analyses with anti-p53 (α-p53), anti-YY1 (α-YY1), or anti–cytoplasmic protein G-6-PDH (α–G-6-PDH) antibodies.