After siRNA-mediated GLI1 silencing in Daoy and U87MG cell lines, expression of PTCH1 decreased, compared with scrambled siRNA-transfected and untransfected cell lines, which may suggest positive regulation of PTCH1 by GLI1 in medulloblastomas and astrocytomas. The gene discussed is PTCH1; the disease is astrocytoma (excluding glioblastoma).