Cortical neurons (day 9) were pretreated with acetaminophen (0 – 500 μM) for 32 h. Cell survival was quantitated by MTT assay. The number of control cells, i.e. viable cells not exposed to any treatment, was defined as 100%. Data are mean ± SD from 3 separate experiments. **p < 0.01 vs. control; ***p < 0.001 vs. control.