The ptn gene promoter contains two AP-1 HREs that are required for the up-regulation of PTN by hydrogen peroxide, nitric oxide, and fibroblast growth factor 2 [7,36,37] and, based on the data of the present study, for the up-regulation of ptn gene transcription by hypoxia in endothelial and cancer cells that express ανβ3 integrin. This evidence concerns the gene PTN and cancer.