RNases abolish the amplification of ITAS only when mixed with a cell extract. Lanes 1 and 2, positive controls (Hela cells, 0.28 μg/assay). Lanes 3 and 4, the Hela cell line (0.28 μg/assay) incubated for 5 hours at RT with 0.02 ng RNase DNase free before the TRAP assay with or without placental RNase inhibitor (1 U/μL) present. Lanes 5 and 6, the Hela cell line (0.28 μg/assay) incubated for 5 hours at RT with 0.02 ng EDN before the TRAP assay with or without placental RNase inhibitor (1 U/μL) present. Lane 7, 20 ng RNase DNase free added to the TRAP assay without cell extract present. Lanes 8 and 9, repeat experiment using 2 and 0.2 ng RNase DNase free, respectively. Lane 10, 20 ng EDN added to the TRAP assay without cell extract present. Lanes 11 and 12, repeat experiment using 2 and 0.2 ng EDN, respectively.