Levels of APP cleaving enzymes in neuron-like differentiated SH-SY5Y neuroblastoma cells. The cells were treated with IL-18 (50, 100, or 150 ng/mL) for described times. (A) BACE-1 (70 kD) increased after 100 ng/mL IL-18 treatment compared to the untreated control (a), (b); the impact of IL-18 was suppressed with IL-18 bp (IL-18 100 ng/mL + IL-18BPa 0.5 μg/mL) (b). (B) IL-18, in a concentration-dependent manner, increased protein level of NTF of PS-1 (34 kD) compared to the untreated control. Protein synthesis of PS-1 (53 kD) increased slightly only at 24 h in IL-18 treated cells. The bands above are likely partially formed γ-secretase complexes including NTF of PS-1. (C) IL-18 treatment increased expression of Pen-2 at 72 h. Arrowheads indicate bands in PS-1 and Pen-2 films co-localized when the Pen-2 and PS-1 films were superimposed. (D) Fe65 (77 kD) increased in 24-h treated cells. (E) Loading control actin for the results B to D, which were obtained from the same membrane. (F) Aph-1 (29 kD) and nicastrin increased in 24-h IL-18 treated cells. The probings are from the same membrane and arranged according to the superimposing. (G) Expression of ADAM10 was generally very low (60 kD active form, 80 kD partially processed, 100 kD precursor). (H) The presence of recombinant IL-18 in 72-h IL-18 treated SH-SY5Y lysate. Actin and Tubulin were used as loading references. Ctrl, untreated control; NTF, N-terminal fragment of PS-1; RcIL-18, recombinant IL-18.