Figure 5. Effects of SNS-032 on CDK7 and CDK9 signalling and RNA polymerase activity in UKF-NB-3 and UKF-NB-3^rSNS-032^300nM cells in the absence or presence of the ABCB1 inhibitor verapamil.

(A) Cropped Western blots indicating RNA polymerase II protein levels, RNA polymerase II phosphorylation at Ser-5 (target of CDK7), RNA polymerase II phosphorylation at Ser-2 (target of CDK9), and levels of anti-apoptotic proteins with a high rate (XIAP, Mcl-1, survivin) in UKF-NB-3 and UKF-NB-3^rSNS-032^300nM cells after 24 h of incubation. β-actin served as loading control. (B) Effects of SNS-032 on the RNA polymerase activity in UKF-NB-3 and UKF-NB-3^rSNS-032^300nM cells in the absence or presence of the ABCB1 inhibitor verapamil after 6 h of incubation. Actinomycin D 100 ng/mL served as positive control. *P < 0.05 relative to non-treated control