Time course of expression changes and apoptosis induction in MM cells treated with 5 μg/ml Onconase. A. Bar graph representative of quantitative RT-PCR expression changes. Human MM cell lines M25, M29, M35, and M42 cells were plated at ~50% confluence, treated with 5 μg/ml Onconase for 0, 24, 48 and 72 h, and RNA was isolated. Error bars represent standard deviation in the expression level of ATF3, IL-24, IL-6, COX-2 and PTOV1 using different concentrations of starting RNA. Results were validated in repeated experiments. Increased levels of ATF3 and IL-24 were consistently observed at all time points. B. DNA fragmentation analysis of MM cells treated in parallel with samples used for quantitative RT-PCR in "A". M29 and M35 were most sensitive to apoptosis induced by 5 μg/ml Onconase at 48 or 72 h time points. Enrichment of DNA fragmentation in Onconase-treated cells was determined by comparisons with untreated cells as per manufacturer's instructions. Error bars depict standard deviation between replicate fragmentation assays.