Fig. 4.

Screening for appropriate concentrations of echinomycin by MTS assays. The viability of PC12 cells was decreased by culturing in 3 % O₂ for 24 h. Echinomycin at 5, 50, and 500 nM was toxic to PC12 cells at 24 and 48 h (a, b). Echinomycin at 0.2 and 1 nM had little effect on PC12 cell viability, whereas 5 and 25 nM echinomycin slightly decreased the viability of PC12 cells (c). VEGF mRNA expression was increased in 3 % O₂ and echinomycin treatment inhibited VEGF mRNA expression dose dependently (d). ***P < 0.001 vs 20 % O₂; ^### P < 0.001 vs 20 or 3 % O₂; “n” indicates the number of parallel wells