Fig. 3. Analysis of the transcriptional status of ETO and AML-1 genes in HEL cells using RT-PCR. Each pair of primers was first tested on total DNA to provide a positive control (`DNA') and then used to amplify the test fragments on the template synthesized by reverse transcription (starting from non-specific primers) of total RNA from HEL cells (`RNA RT+'). The lanes designated `RNA RT–' represent a negative control loaded with amplification products synthesized without a cDNA template. All reactions were set up as in the previous case, but the reverse transcription enzyme was omitted from the first-strand synthesis mixture. Molecular sizes of the marker bands are shown at the right side of the lane loaded with the marker (M).