S100A8 and prostate cancer: Enhanced secretion of S100A8/A9 in a hypoxic environment may be mediated by hypoxia-induced factor 1 (HIF-1), as HIF-1 was reported to upregulate transcriptional levels of S100A8/A9 in prostate cancer cells by directly activating the S100A8 and S100A9 promoters (Grebhardt et al., 2012).