Electropherograms to assess quality of RNA prepared from microdissected cells. RNA integrity is tested using the Agilent bioanalyzer, and only intact RNA is used for performing microarray assays. (a) Intact RNA that is properly diluted, though of a low concentration (see
Note 8). The 18S rRNA fluorescent peak appears at about 2,000 nucleotides, and the 28S rRNA peak is just under 4,000 nucleotides. (b) Intact RNA that is not diluted can appear as though it is partially degraded, with peaks between the 18S and 28S rRNA peaks. (c) Partially degraded RNA may contain an apparent 18S rRNA peak, but no 28S rRNA peak. (d) RNA that is contaminated with DNA will have a broad 28S rRNA peak, or two peaks near the 28S rRNA peak