Loss of Bim prevents spontaneous and LPS-induced nfkb1^−/− B-cell apoptosis. wt, nfkb1^−/−, bim^−/−, and nfkb1^−/−bim^−/− B cells were cultured with or without LPS for 48 hours. (A) Spontaneous apoptosis after 24 and 48 hours. (B) B-cell death after LPS stimulation over 48 hours. Results represent the mean plus or minus SEM of 5 experiments.