For the labeling of siRNA with Cy3. Includes sufficient reagents for labeling 65 μg of siRNA. Ambion Labeled siRNA can be used to analyze siRNA subcellular localization, stability, and transfection efficiency. In addition, fluorescently labeled siRNA is particularly well-suited for use in double-label experiments (with a labeled antibody) to track cells that receive siRNA during transfection and to correlate transfection with down-regulation of the target protein. Research shows that labeling of siRNAs does not affect their biological function.