The hypoxia-inducible factors-α (HIF-α) (including HIF-1α and HIF-2α) regulate the adaptation of tumor- and metastasis-initiating cells to the oxygen and nutrient deprivation in tumor progression under normoxic and hypoxic conditions (Schönenberger and Kovacs, 2015; Li et al., 2019). Here, HIF1A is linked to neoplasm.