Effects of melphalan on MM cells in vitro. (A) Real-time quantitative RT-PCR analysis of RAD51, its paralogs and BRCA1 transcripts in H929 cells, was performed 24 h after indicated treatments. GAPDH was used as the internal control and the mRNA levels normalized to control (DMSO) samples. (B) Flow cytometric analysis of propidium iodide stained cells treated as indicated in (A) was performed. **, *** and ****P < 0.01, 0.001 and 0.0001, respectively, relative to DMSO treated group.