Figure 2. Cytotoxicity of shikonin ester derivative PMM-034 on rhabdomyosarcoma cell viability. PMM-034 was serially diluted to 0, 2.5, 5, 10, 20, 50, 100, 200, and 400 μg/mL in DMEM containing 2.5% FBS. Subsequently, the cytotoxicity of PMM-034 on RD cells was determined by the WST-1 assay. Data are reported as means ± standard deviation (SD) from at least three independent experiments. The red dot indicates the PMM-034 concentration under 50% cell survival rate.