5-azaC incorporates into RNA. Extracted ion chromatograms for: (A) RNA hydrolysate from a blank cell sample treated with NaBH₄ (scale is enhanced). Arrows show the approximate locations of the ion peaks. (B) RNA hydrolysate from 5-azaC–treated cell sample followed by treatment with NaBH₄. (C) RNA hydrolysate from blank cell sample treated with NaBD₄ (scale is enhanced). Arrows show the approximate location of the ion peaks. (D) RNA hydrolysate from a 5-azaC–treated cell sample followed by treatment with NaBD₄. To simplify the figure, the 5-azaC channel is not shown.