Can Uracil-N-Glycosylase (UNG) be used with a one-step RT-PCR kit, such as the QuantiTect Probe RT-PCR Kit?

No. Uracil-N-Glycosylase will remain active during the reverse-transcription step with the QuantiTect Probe RT-PCR Kit, and destroy any newly synthesized cDNA. Heat-labile UNG is required for one-step RT-PCR. See also FAQ 564 for further info.