Figure 1.

Arsenite concentration lethal to 50% of cells (LC₅₀) values derived from in vitro assays using the trypan blue dye exclusion method. Cell viability curves for A) RWPE-1 cells and B) WPE-stem cells in response to exposure to various concentrations of arsenite for 72 hours among cells previously unexposed to arsenite (circles) and cells previously exposed to 5 μM arsenite for 6 weeks (triangles) were used to determine innate and adapted LC₅₀ values. C) Innate and adapted LC₅₀ values for RWPE-1 (open bars) and WPE-stem (closed bars) were derived from survival curves after log₁₀ conversion. Data are presented as mean LC₅₀ values (n = 3 for innate; n = 6 for adapted); error bars correspond to 95% confidence intervals. P values are two-sided (Student t test).