CXCR4 and leukemia: Integrin binding and CXCR4 chemokine receptor activation are important for migration of CD34+ hematopoietic progenitors and AML cells to marrow stroma cells [31], and leukemia cells may utilize CXCR4 to access niches that are normally restricted to progenitor cells, and thereby home into a microenvironment that favours their growth and survival [31,32].