Islet cell apoptosis after culture in the presence of 1% serum. Isolated islets were cultured for 18 hr in the absence or presence of the cytokines indicated. The islets were then fixed and processed for TUNEL staining, which detects apoptosis by visualizing DNA strand breaks. Percent TUNEL-positive nuclei is given as mean ± SEM for 4 to 5 determinations. **p < 0.01 when compared with Shb-transgenic islets in the absence of cytokines using a paired Students t-test.