CXCR4 and acute lymphoblastic leukemia: Importantly, CXCR4-CXCL12 signaling supports as well the interaction of leukemic cells with the BM microenvironment, regulating the survival and progression of NOTCH1-induced mouse and human T-ALL cells and the expansion of human T-ALL xenografts mediated by LICs [92,111,112,237].