Therefore, we first investigated the effect of IL-17 on GFAP in human astrocytoma cell lines, by incubating U251 cells with various concentrations of IL-17 for 24 h (Fig. 1a and c) and 100 ng/ml IL-17 for different hours (Fig. 1b and d). The gene discussed is IL17A; the disease is astrocytoma (excluding glioblastoma).