IGF-I, insulin ? like growth factor I, seems to play a major role in the normal and tumoral development of the nervous system. Glioblastoma is the most frequent brain tumor in man and is usually fatal. Both human and rat glioma cells express high amounts of IGF-I. When rat glioma cells are transfected with vectors expressing either IGF-I antisense RNA or inducing IGF RNA ? DNA triple helix, the synthesis of IGF-I was stopped on translation or transcription levels, respectively. Down-regulation in the expression of IGF-I coincides with the reappearance of B-7 and MHC class I antigens at the surface of transfected cells. When injected subcutaneously, the transfected cancer cells initiate an immune reaction involving CD8+ lymphocytes, followed by tumor regression. The ?anti-gene? strategy for clinical therapy of glioblastoma, and other tumors expressing IGF-I such hepatomas were introduced in University Hospitals of Cleveland (USA), Shanghai ( China) , Krakow and Bydgoszcz (Poland).