IL-18 activates p-p38 and p-ERK½ in a time-dependent manner. Monocytes (5 × 106 cells) were stimulated with 2.5 nM rhuIL-18. Cell lysates were made and probed for p-p38 and p-ERK½ with Western blot, showing marked increases in phosphorylation after 5 minutes for p-p38 and 15 to 30 minutes for p-ERK½. Representative blots show both p-p38 and p-ERK½ (upper panel for p-p38 and lower panel for p-ERK½). Graphs for p-p38 and p-ERK½ were normalized by respective total cellular expression for both signaling molecules relative to the untreated control blots (n = the number of blood donors, and graphs show combined data from five separate experiments). In total, five separate experiments were completed by using peripheral blood monocytes from four separate volunteers.