The basic principles of the Two-Cycle Target Labeling Assay are very similar to the One-Cycle Standard Protocol, and many of the steps involved may look familiar. However, since it does require manipulation of very small amounts of materials in the 1st cycle, even the most experienced GeneChip microarray users may not obtain ideal data when using the Two-Cycle protocol the first time.

Therefore, it is suggested that users first read the protocol very carefully, including all notes and tips, and then practice initially with diluted samples that you have previously characterized using the One-Cycle Standard Protocol. This way, you will be starting with materials of good quality and you already know what results to anticipate. Follow common laboratory practices that minimize RNase contamination and use caution at each step to prevent sample loss.