IFN-α and -β induce Bid and Bcl-2 cleavage.

U266 cells were treated and harvested at the indicated times (T) in the presence or absence of z-VAD-fmk. (A) Bid and Bcl-2 were analyzed by Western blotting using a Bid pAb (a kind gift from X. Wang, UT Southwestern22) and Bcl-2 mAb. z-VAD-fmk was added every 24 hours following IFN treatment. The data shown are representative of 3 different experiments. (B) IFN-α and -β, but not -γ, induce Bcl-2 cleavage in U266 (left) and freshly isolated MM cells (right). Plasma cells were isolated from patients and treated for 48 hours, before being subjected to Western blotting for Bcl-2. (C) U266 cells were treated as indicated and then subjected to Western blotting with the appropriate antibodies for Bcl-x_L, Bad, Bak, and Bax, and, as a control, β-actin.