IL-5 is unable to suppress apoptosis or induce Mcl-1 in TF-1 cells.

(A) IL-5 suppressed apoptosis in JYTF-1, but not in TF-1 cells. TF-1 (lanes 2-8) and JYTF-1 (lanes 9-15) cells were transferred from medium containing GM-CSF (lanes 2 and 9) into medium containing IL-5 for various time periods (lanes 3-7 and 10-14) and were subjected to DNA ladder analysis. Two DNA samples from cells kept in 0.5% FBS cytokine-free medium for 24 hours were used as controls (lanes 8 and 15). DNA samples were fractionated in 1.5% agarose gel. Mr indicates molecular weight marker. (B) IL-5 sustained Mcl-1 expression in JYTF-1, but not in TF-1 cells. TF-1 (lanes 1-7) and JYTF-1 (lanes 8-14) cells were treated as described in panel A. Cell lysates were prepared from cells at each time point and subjected to Western blot analysis for the protein expression of Mcl-1, Bcl-2, Bcl-X_L, Bax, and α-tubulin probing with antibodies specific for each antigen. The immunoblots were visualized using an ECL system. Experiments were repeated 3 times and a representative result is shown in this figure. (C) Expression of Mcl-1, but not of Bcl-X_L, is stimulated by GM-CSF, IL-5, or SCF in JYTF-1 cells. JYTF-1 cells were deprived of cytokines for 24 hours (lane 1) and restimulated with GM-CSF (lane 2), IL-5 (lane 3), or SCF (lane 4) for 1 hour. Cell lysates were analyzed as described in panel B, except that only Mcl-1, Bcl-X_L, or α-tubulin levels were probed with specific antibodies.