Through our research, we want to understand how environmental cues control the blood stem cell, with the hope of designing better blood stem cell transplantation therapies for the treatment of immune deficiency and cancer. In collaboration with Dr. Camilla Forsberg, an assistant professor of biomolecular engineering in the Baskin School of Engineering at UC Santa Cruz, we have demonstrated that hematopoietic stem cells use a molecule called Robo4 to anchor themselves in the bone marrow. Robo4 acts as an adhesion molecule, interacting with other components of the bone marrow to bind the stem cells into their proper niche. Moreover, another molecule called Cxcr4, cooperates with Robo4 to retain hematopoietic stem cells in the bone marrow. However both molecules appear to act through different molecular mechanisms. Their inhibition would be a good way to achieve efficient mobilization of hematopoietic stem cells. We consider these findings may lead to improvements in the safety and efficiency of bone marrow transplants.