The only drug used to mobilize stem cells into the blood of health donors for collection is G-CSF. However there is a new mobilization drug recently approved called plerixafor. This drug is able to mobilize stem cells when G-CSF has failed and pre-clinical studies suggest that it may produce a superior stem cell graft to G-CSF alone. There is little information available, besides safety and efficacy data, about the effects that plerixafor has on the stem cell graft of normal healthy donors.