Koshikawa et al. reported that ROS generated in mitochondria upregulated the transcription of the HIF-1α gene via the phosphatidylinositol 3 kinase-Akt/protein kinase C/histone deacetylase (PI3K-Akt/PKC/HDAC) pathway, leading to the accumulation and activation of HIF-1α in tumor cells [33]. Here, HIF1A is linked to neoplasm.