Both cytoplasmic domains of Igα and Igβ are necessary to induce cell death. (A) Flow cytometric analysis of cell death induced in wild-type WEHI-231 (WT) and an α/α//β/β transfected clone. Shown are dot plots of forward scatter (FSC) versus propidium iodide (PI) staining for a typical experiment. (B) Analysis of cell death in all transfectants. The mean and standard deviation derived from three experiments is shown. For each experiment, the percent change in cells stained with PI upon stimulation was determined by subtracting the percentage of PI^high (as gated in A) cells in unstimulated populations cells from that in the corresponding stimulated populations. This number was then expressed as a percentage of the cell death obtained from stimulating the wt BCR (% maximum). “Ig” refers to BCR and “Ch” refers to the chmeras. *Indicates values that were significantly different (P < .01, two-sided t-test) from those obtained from wild-type cells.