Sp1 is a ubiquitous nuclear factor that plays a key role in maintaining basal transcription of 'house-keeping' genes. It has been demonstrated that Sp1 is involved in many cellular process, e.g.cell growth and differentiation. Sp1 plays an extremely important role in growth and metastasis of many tumors by regulating oncogenes, tumor suppressor genes, cell cycle control molecules, growth-related signal transductions, angiogenesis-related factors, as well as apoptosis. The expression of Sp1 and its activity are strictly regulated. Mechanisms include the modulation of Sp1 and interactions between Sp1 and other molecules. New treatment with Sp1 as the target will bring profound impacts on the strategy of clinical chemotherapy of tumor.