HLFs were infected with lentiviruses pAB319 and pAB322 expressing MRG15 and MRGX small hairpin RNAs from the H1 polIII promoter. RNA was amplified by one round of T7 transcription and labelled by reverse transcription in the presence of Cy3 and Cy5 dCTP. The pAB319 shRNA induces an artefactual interferon response.