Pushing stem cells out of the bone marrow into the bloodstream so they can be collected for transplantation.Stem cell mobilization is the pharmacological release of hematopoietic stem and progenitor cells (HSPCs) from bone marrow into peripheral blood for collection via apheresis. The CXCR4/CXCL12 axis is the primary retention mechanism—CXCR4 on HSPCs binds CXCL12 (SDF-1) on marrow stromal cells. Motixafortide (BL-8040) is a CXCR4 antagonist that disrupts this interaction, mobilizing stem cells for autologous transplantation. G-CSF is the standard mobilization agent; CXCR4 antagonists provide rapid, complementary mobilization.