After the last apheresis has been completed, or after the patient has collected ≥2*10^6 CD34+ cells/kg, he/she will be treated with high-dose chemotherapy in preparation for transplantation. Patients will be transplanted with cells obtained from the G-CSF with plerixafor mobilization regimen. In the event that the minimum number of ≥2*10^6 cells for transplantation are not obtained from the first mobilization with plerixafor, cells may be retained and pooled for transplantation with those from a second mobilization with plerixafor (or from prior mobilization with other agents), at the investigator's discretion. If a second mobilization with plerixafor is attempted, a minimum rest interval of one week should be allowed between the last apheresis of the first regimen and the first dose of G-CSF of the second. The number of CD34+ cells mobilized in the peripheral blood (PB), collected in the apheresis product, and the number of apheresis sessions performed will be measured. Success of the transplantation will be evaluated by the time to engraftment of polymorphonuclear leukocytes (PMN) and platelets (PLT). Participants will be assessed for durability of their transplant for 12 months after transplantation.