NOS2 and neoplasm: Conversely, in hypoxic tumor regions, PHD activity is inhibited, leading to stabilization of HIF-1α, which translocates into the nucleus, heterodimerizes with Aryl Hydrocarbon Receptor Nuclear Translocator (ARNT), and binds to hypoxia-responsive elements (HREs) within the iNOS promoter (at approximately −1164/−1158 bp).