To improve our therapies in multiple myeloma, we need to understand the molecular proteins that are involved in the malignant cells. We propose to study the PI3kinase proteins and their interaction with the receptor CXCR4. Our aims are to determine the level of the proteins in the malignant plasma cells compared to normal plasma cells, and the activity of the CXCR4 receptor and the PI3kinase pathway in the movement of the malignant cells in the bone marrow. This proposal is strengthened by the use of cells obtained from patients in correlation with a clinical trial using a PI3 pathway inhibitor.