A Kobe University research group including graduate student Ishii Shinichi and Associate Professor Katayama Yoshio (both of the Department of Hematology, Graduate School of Medicine) have discovered that fibroblast growth factor-23 (FGF23) produced by erythroblasts (cells that are the precursors of red blood cells) promotes the movement (mobilization) of hematopoietic stem cells into the peripheral blood. Up until now, FGF23 has been known for the role it plays in the kidneys as a hormone which regulates phosphate concentrations throughout the body.