PTEN and prostate cancer: Although VEGF, another key angiogenesis regulator and secretory protein induced by HIF1α [17], was not identified by the microarray analysis as being upregulated by Klf5 deletion, our expression analyses demonstrated that KLF5 loss indeed upregulated HIF1α at the protein level and VEGF and PDGF at both the mRNA and protein levels in both mouse prostate tumors and human prostate cancer cells with deficient or insufficient PTEN (Figure 2, 3 and 5).