Downregulated Pten occurred in both the ROS and HIF-related cancer signal pathways (Figures 4B, C); the expression of some HIF target genes, such as Kras (Kirsten rat sarcoma 2 viral oncogene homolog, GTPase KRas oncogene), was also downregulated in the HIF-related cancer signal and HIF pathway. This evidence concerns the gene PTEN and cancer.