Stabilization of SOCS3 and β-catenin by CKIϵ. 32D transfectants were treated with 5 ng/mL IL-3 or 10 ng/mL G-CSF in the absence or presence of MG132 (20 or 40 μM) for the indicated times. Then, total cell lysates were subjected to immunoblot analysis (IB) by using anti-SOCS3 and β-actin (^*) (A), anti-CIS (B), and anti–β-catenin (C) polyclonal antibodies. To detect CIS protein in the absence of MG132, the immunoblot filter was exposed for a long time. Equal loading of cell lysates in each lane was probed with an anti–β-actin antibody. The same lysates were employed in IB for CIS and β-catenin.