Constitutive activation of the ERK/MSK/Sp1 axis was required for survivin expression in CD34+ AML samples. (A) LSCs were treated with the JNK inhibitor SP600125 (0, 25, 50, or 100 μM), the ERK inhibitor U0126 (0, 25, 50, or 100 μM), or the p38 inhibitor SB203580 (0, 5, 10, or 20 μM) for 48 h, and survivin protein expression was analyzed by immune-blotting. (B) The phosphorylation levels of ERK and MSK, as well as the protein expression level of Sp1, were analyzed in six paired CD34+ AML samples by immune-blotting, and GAPDH was used as an internal control. (C) The density of each protein band was quantified, and the lines indicate the tendency of altered levels of p-ERK, p-MSK, and Sp1 in each paired sample. (D) Analysis of MSK activation following treatment with TNF-α or the ERK inhibitor U0126. (E) Analysis of Sp1 activation following stimulation with TNF-α or the ERK inhibitor U0126. Results were confirmed using the NT-KD MSK vector and the WT MSK vector. (F) Analysis of survivin mRNA following treatment with TNF-α, U0126, or NT-KD MSK in LSCs (*
P < 0.05, **
P < 0.01).