To determine if cells driven by EWS-FLI1 are more sensitive to actinomycin D, we assessed cell growth and viability using a MTT assay after 44 hrs exposure to actinomycin D. Although all cell lines were affected by actinomycin D, the Ewing sarcoma cell lines were as a group more sensitive by comparison to other cell lines tested (Figure 5). Here, EWSR1 is linked to Ewing sarcoma.