Malignant solid tumors contain hypoxic regions due to uncontrolled proliferation of cancer cells and insufficient formation of a vascular network. Accumulating evidence has suggested that hypoxia-inducible factor 1 (HIF-1) functions in not only cellular adaptive response to hypoxia but also malignant progression and chemo-/radio-resistance of cancer cells. However, gene networks responsible for the activation of HIF-1 have not yet been fully elucidated, which makes it difficult to develop novel therapeutic strategies for cancers. We aim at identifying novel HIF-1-related and hypoxia-dependent gene networks and utilizing them as rational targets for cancer therapies.