Given the enrichment of HIF-1α and AHR gene signatures in Eμ-TCL1 mice compared to WT mice, their important role in cancer, and their ability to heterodimerize with the same binding partner called HIF-1β/Arnt [35,36], we decided to study the role of both AHR and HIF-1α in leukemogenesis in the Eμ-TCL1 murine model of CLL. This evidence concerns the gene HIF1A and cancer.