The present invention provides for compositions and methods for administering one or more UDP compound, alone or in combination with another hematopoietic progenitor cell mobillizing compound (for example, but not limited to, G-CSF), to mobilize hematopoietic progenitor cells for transplant or other purposes. The methods of the invention may be particularly advantageous as applied to improve the stem cell yield in so-called “poor mobilizing” patients.