Table 3. Benchmark etoposide cytotoxicity in EWS cell lines.

Cell line	Efficacy (EC50) µM	Sensitivity24 hrs % dead cells per nM morpholino (r2)	Fraction dead cells at 24 hours (FA24 hs)†
HEK293 (control)	0.73	0.068 (0.895)	0.16 ± 0.01
TC-32	0.64	0.078 (0.900)	0.26 ± 0.05*
CHLA-9	0.43	0.117 (0.889)	0.32 ± 0.03*
CHLA-10	0.32	0.156 (0.915)	0.41 ± 0.05*

^†Fraction Dead Cells at 24 hours (FA_{24 hrs}) represents the activity of the agent and is calculated for individual cell lines using the fraction of cells lost among 5 biological replicates at the most potent concentration of etoposide, corrected to the average fraction of cells lost using a DMSO vehicle control only; All replicates were measured on the same 96-well tray and were seeded with an identical number of starting cells, 24 hours prior to etoposide treatment (see methods).

^*p < 0.05, based on paired student t-test comparing mean corrected activity (FA_{24 hrs}) at 24 hours.