HBx upregulates Hsp90α expression by activating c-Myc. (A) Lysates from stable cell lines, HepG2-pcDNA3 (lane 1) and HepG2-pcDNA3-X (lanes 2-4) after either mock treatment (lanes 1-3) or treatment with 200 nM U0126 (lane 4) for 4 h were prepared, and the protein levels of c-Myc, ERK1/2 and phosphor-ERK-1/2 were detected by Western blot analysis. GAPDH was included as an internal control. (B) Total RNA purified from HepG2-pcDNA3 (lane 1) and HepG2-pcDNA3-X (lanes 2-4) after either mock treatment (lanes 1-3) or treatment with 5 mM 10058-F4 (lane 4) for 24 h was subjected to RT-PCR to measure the RNA level of c-Myc, HBx and GAPDH. (C) Western blot analysis was performed to measure the levels of c-Myc, HBx and GAPDH in the cells prepared as described above. (D) HepG2-pcDNA3-X cells were transfected with 100 nM of either control siRNA, c-Myc siRNA or in a combination and Western blotting analysis was performed.