2.3. Western blotting

K562 cells were lysed with 1X passive lysis buffer (Promega, Madison, WI) and total protein was quantified with a BCA protein assay kit (Pierce, Rockford, IL). The extracted proteins were separated on a 10% SDS-PAGE and then transferred to Nitrocellulose membranes (Whatman, Maidstone, Kent). After blocking in 1x TBS-Tween 20 containing 5% nonfat milk (5% TTBS) (Difco Franklin Lakes, NJ), membranes were probed with specific antibodies (in 5% TTBS) for K_v2.1, K_v3.3, p38, phospho-p38 (Abcam, Cambridge, MA), K_v1.2, K_v1.3, CREB, phospho-CREB (Millipore, Billerica, MA), ERK, phospho-ERK (Cell Signaling Technology, Inc, Danver, MA), K_v9.3, c-fos or β-actin (Santa Cruz Biotechnology, CA, USA). After overnight incubation, membranes were treated with horseradish peroxidase-conjugated goat, anti-rabbit secondary antibody (Santa Cruz Biotechnology, CA, USA) and visualized using an enhanced chemiluminescent detection kit (iNtron Biotechnology, Gyeonggi-do, Korea)