Effects of 30 μM chlorpyrifos (A), diazinon (B), dieldrin (C) or Ni2+ (D) exposure on expression of genes involved in the synthesis, storage and degradation of ACh. For chlorpyrifos, results are shown for both undifferentiated cells (U 24h, U 72h) and cells undergoing NGF-induced differentiation (D 24h, D 72h), whereas results for the other agents involve only differentiating cells. Asterisks shown below each gene denote a significant main treatment effect. Daggers denote genes for which treatment interacted with the other variables (differentiation state, time) and show the individual values for which treatment effects were present.