Effect of Ilantide on neurite outgrowth from cerebellar granule neurons. Cerebellar granule neuron cultures were treated with interleukin 1 receptor antagonist (IL-1Ra) (A), soluble interleukin 1 receptor type I (sIL-1RI) (B), Ilantide-t (C) or IL-1β (D) for 24 hours. The cultures were fixed and immunostained with rabbit anti-rat growth-associated protein 43 (anti-GAP-43) primary antibodies and then with secondary Alexa Fluor 488 goat anti-rabbit antibodies. (E) Effect of IL-1β on neurite outgrowth induced by IL-1Ra. (F) Effect of IL-1β on neurite outgrowth induced by Ilantide-t. The results from three to four independent experiments are expressed as percentage ± SEM with untreated controls set at 100%, corresponding to an average neurite length of 19.3 ± 4.1 μm. *P < 0.05 and **P < 0.01 compared with untreated controls (A to D) or cultures treated with either IL-1Ra or Ilantide alone (E and F) by one-way analysis of variance followed by the Newman-Keuls post hoc test).