ARNT and neoplasm: Hypoxia-Inducible Factor (HIF), a protein complex composed of either HIF1a or HIF2a and HIF1b/ARNT subunits, activates genes involved in angiogenesis and cell proliferation, and is central to the tumor’s adaptation to low oxygen, contributing to a neoplastic phenotype (LaGory and Giaccia 2016; Akhtar et al. 2018).