Curcumin activity. Curcumin inhibits the growth/viability of human multiple myeloma cell line U266 and bone marrow CD138⁺ multiple myeloma cells (A-D). Cell line U266 (A) or enriched CD138⁺ cells (2 × 10⁴/0.1 mL) from bone marrow aspirates of multiple myeloma patients (nos. 7, 9, and 10) (B-D) were cultured in the absence or presence of the indicated concentrations of curcumin for 24 hours, and cell viability was measured by MTT assay (A-B) or standard trypan blue dye exclusion method (C,D) as described. Curcumin inhibits the expression of Bcl-2 and Bcl-X_L proteins in human multiple myeloma cell line U266 (E) and bone marrow CD138⁺ multiple myeloma cells (F). A total of 2 × 10⁶ U266 cells (E) or CD138⁺ multiple myeloma cells (F) were treated with curcumin (50 μM) for the indicated times, prepared the cytoplasmic extracts, resolved the 50 μg cytoplasmic extracts on 10% SDS-PAGE gel, electrotransferred on a nitrocellulose membrane, and probed for Bcl-2 and Bcl-X_L by Western blot analysis. β-actin was used as a loading control. Values represent the mean ± SD of triplicate cultures.