Sp1 is one of the nuclear transcription factors which are widely expressed in human body.It plays an important role in human growth and physiological activities,and is highly expressed in many kinds of tumors'tissue.Sp1 participates in regulating growth,invasion,angiogensis actions of tumor by regulating downstream gene(s) transcription.Some grow factors and tumor suppressor genes can regulate the expression of VEGF by Sp1,and then participate in angiogensis of tumor by two main mechanisms:kinases inducing Sp1 phosphorylation and the interact of Sp1 and other proteins.