While there are four Sp1 binding sites in the core promoter region, mutation of a single binding site, Sp1.4, eliminated androgen induction of this region of VEGF. The VEGF promoter is similar to the NRIP promoter, in that both are TATA-less GC rich promoters that are induced by androgen in prostate cancer cells [29]. Here, SP1 is linked to prostate cancer.