SOCS3 is required for HBx-induced IRS1 protein expression.

<p>(A) The degradation of IRS1 by cooperation between HBx and SOCS3. <i>Top</i>; Mock and HBx-constitutively expressing HepG2 cells were transiently transfected with Myc-tagged SOCS3. 48 hours after transfection, the cell extracts were immunoblotted with the IRS1-specific antibodies. <i>Bottom</i>; Image analysis of IRS1 protein expression by densitometry. (B) The effect of HBx and SOCS3 siRNA on IRS1 protein expression. <i>Top</i>; Mock and HBx-constitutive expressing HepG2 cells were transiently transfected with pSUPER/GFP control or pSUPER/SOCS3. The cell extracts were immunoblotted with the IRS1-specific antibodies. <i>Bottom</i>; Image analysis of IRS1 protein expression by densitometry. Values were expressed as the means ± SD. *<i>P</i><0.05 and **<i>P</i><0.01 compared with indicated controls.