HIF1A and prostate neoplasm: Since NIR dye uptake was mediated by OATP channel proteins whose expression was regulated by HIF-1α, which in turn was controlled by hypoxia, a common known pathologic condition in tumor growth, we detected HIF-1α and OATP2B1 protein expression in prostate tumor tissue xenografts but not normal tissues by immunohistochemical (IHC) staining (Figure 3E), suggesting similar mechanisms may be responsible for NIR dye uptake by freshly harvested human PCa tissues and cultured cells.