Fresh myeloma cells were purified from the bone marrow (BM) of refractory MM patients by flow sorting of CD38⁺CD45⁻ cells. Myeloma cells with a purity of more than 97% were routinely obtained.16 Sorted cells were cultured for 3 days in FCS medium with 5 μg/mL Bcl-2-ASO, followed by an additional 2 days of culture with or without 2 μM DEX. Bcl-2-ASO was replenished every 2 days in cultures with Bcl-2-ASO. Apoptosis was determined by annexin V following 4 and 5 days of culture with Bcl-2-ASO alone; following 1 or 2 days with DEX alone; or following 3 days of treatment with Bcl-2-ASO, followed by 1 or 2 days of DEX. M1 through M10 represent myeloma cells sorted from 10 refractory MM patients. In MM patients tested, Bcl-2-ASO potentiated DEX-induced apoptosis. Background apoptosis in myeloma cells before treatment was less than 5%.