HIF1A and neoplasm: Importantly, as the genes encoding murine and human HIF-1α were not found to be up-regulated in the absence of IKKα in our murine and human NSCLC in vivo models, IKKα would then appear to act as an NSCLC tumor suppressor in an indirect manner by suppressing the accumulation and/or stability of HIF-1α protein under hypoxic conditions.