This is because CXCR4 signaling is essential to maintain the leukemic stem cell phenotype, playing a crucial role in the retention and protection of leukemic cells in the BM niche, which is associated with resistance and relapse that two-thirds of chemotherapy-treated AML patients experience [7,11,54,55,56]. The gene discussed is CXCR4; the disease is acute myeloid leukemia.