Figure 5.

The extracellular signal-regulated kinase (ERK) pathway inhibitor PD98059 interferes with the CD38-induced apoptosis in CD38-transfected Ba/F3 cells. (a) CD38-transfected Ba/F3 cells (10⁶) were pre-incubated for 30 min with either DMSO (upper panel) or the inhibitor PD98059 (20 µm, lower panel). The cells were stimulated with anti-CD38 (NIMR5), rat IgG or left untreated for 4 hr at 37° in the constant presence of vehicle or inhibitor. After stimulation, the cells were transferred to FACS tubes and Annexin-V/propidium iodide staining was performed as described in the Materials and methods. The cells were resuspended in 300 µl binding buffer and immediately captured using a FACSCalibur cytometer (Becton Dickinson). (b) Graph of percentages of Annexin-V/propidium iodide-positive cells. The averages ± SD from three independent experiments is shown. The groups were compared using unpaired Student's t-test and one-way analysis of variance, and P-values ≤ 0·05 were considered significant. PD98059 (−): absence of inhibitor; PD98059 (–): presence of inhibitor. Anti-CD44 was used as control (IgG2a).