ARNT and cancer: In contrast, HIF1α protein is hydroxylated and degraded under normoxia, but rapidly accumulates and forms a heterodimer with HIF1β to regulate gene expression in response to the hypoxic microenvironment.[85] When stimulated by inflammatory mediators or cytokines secreted by immune cells in the tumor microenvironment, the inflammation‐associated TF Nuclear Factor kappa‐B (NF‐κB) in cancer cells is activated, leading to the upregulation of genes that regulate cancer proliferation and metastasis.