CD34 and plasma cell myeloma: In summary, we have found that in patients with multiple myeloma, using a threshold of 1 x 106 CD34 +ve viable cells / Kg of the recipient has allowed us to define a suboptimal mobilization which presents in one quarter of patients and seems to be associated with previous treatment with oral melphalan, previous autograft with intravenous melphalan and previous treatment with bortezomib, and that the long term overall survival of the poor mobilizers seems to be worse than that of individuals grafted with 1 x 106 CD34 +ve viable cells / Kg of the recipient.