Our flow cytometric apoptosis assay showed that the combination of drugs with IFN-α significantly increased the rate of apoptosis in drug sensitive cells but did not affect apoptosis in drug-insensitive cells (Figures 2F, G), suggesting that doxorubicin-sensitive MM cell lines responded to IFN-α and combined therapy could further promote apoptosis of myeloma cells in vitro. This evidence concerns the gene IFNA1 and plasma cell myeloma.