Contribution of α-T3E-dependent STAT3 inactivation to the inhibition of proteasome subunits in H2452 cells. (a) Cells were treated with α-T3E (20µM) for 24 h, and STAT3 and phosphorylated P-STAT3 protein levels were assessed by immunoblotting. The α-Tubulin protein levels served as the loading control. A densitometric analysis was performed as described in Section 4.7. The data are means ± SD, n = 3. ** p < 0.01 vs. the control. (b) Cells were treated with α-T3E (20 µM) for 24 h, and the mRNA levels of BCL-2 and BCL-XL were assessed by real-time quantitative PCR as described in Section 4.6. The data are means ± SD, n = 3. * p < 0.05 vs. the control. (c) Cells were treated with α-T3E (20 µM) for 24 h, and the mRNA levels of proteasome subunits were assessed by real-time quantitative PCR. The data are means ± SD, n = 3. ** p < 0.01 vs. the control. (d) Cells were treated with niclosamide (10 µM) for 24 h, and the mRNA levels of proteasome subunits were assessed by real-time quantitative PCR. The data are means ± SD, n = 3. ** p < 0.01 vs. the control.