Figure 3.

The relationship between SOX9 and Raf/MEK/ERK signaling pathway. A: Dual luciferase reporter gene assays with constructs carrying wild-type MEK1, MEK2, ERK2 promoter containing the SOX9 binding site. The relative luciferase activity (firefly/Renilla) significantly increased with PGL3-MEK1-wt, but not with PGL3-MEK2-wt, PGL3-ERK2-wt and deletions of seed sequences of PGL3-MEK1/MEK2/ERK2-wt (PGL3-MEK1-del1/2, PGL3-MEK2-del1/2 and PGL3-ERK2-del1/2 respectively) (mean±SD of three independent experiments, P < 0.05). B: Co-treatment of si-SOX9-1 and Sorafenib (10uM, 15uM)/Sunitinib (2 uM, 3 uM) significantly decreased expression of MEK1 and its phosphorylated protein (p-MEK1/2, p-ERK1/2) as assayed by RT-PCR and qPCR (with β-actin as internal control) and Western blot (with GAPDH as internal control).