CXCR4 and plasma cell myeloma: Targeted disruption of the CXCR4-CXCL12 and VLA4-VCAM1 axes with CXCR4 or VLA4 antagonists has been explored to enhance the efficacy of chemotherapy against both hematological (acute myeloid leukemia, acute and chronic lymphoid leukemia, and multiple myeloma) and non-hematological malignancies.