Protein levels of indicators of apoptosis in differentiated SH-SY5Y cells. The cells were treated with IL-18 (100 ng/mL) for described times. IL-18 (A) decreased pro-caspase-3 (approximately 32 kD) at 6 h, but increased its level in 72-h treated cells. The approximate 58 kD form, which is likely the active form composed of two 12 and 17 kD fragments of caspase-3, increased very slightly in 72-h treated cells. (B) Bcl-xL, which inhibits activation of caspases, was slightly reduced at 6-h IL-18 treated cells but induced in 72-h timepoint. Actin was used as a loading control.