This study will examine whether 240 µg/kg plerixafor given alone for up to 4 days is safe and well tolerated in multiple myeloma (MM) patients. In addition, this study determines if plerixafor alone can be used to mobilize peripheral blood progenitor cells (PBPCs) for transplantation in MM patients. The minimum number of CD34+ cells to collect is 2*10^6 CD34+ cells/kg and the target is ≧4*10^6 CD34+ cells/kg. Success of transplant engraftment will be measured by the number of days to polymorphonuclear leukocytes (PMN) and platelet (PLT) engraftment. Durability of transplant will be assessed for a minimum of one year.