Transiently transfected and integrated LTR reporter systems exhibit increased transactivation in the absence of SETDB1. A) Transient transfection of the CAT assay is broken down as follows: Lane 1 indicates the negative control; Lanes 2–4 titration of Tat from 0.01, 0.1 and 1.0 ug to establish a range of activation; Lanes 5–10 are in the presence of 0.1 ug Tat as well as the indicated transfected siRNAs. B) TZM-bl cells containing an integrated LTR-Luc were transfected with siGFP, siSETDB1, siTIF-1, siG9a, and siHP1 in addition to Tat (0.1 ug) to initiate transcription. Confirmation of the knockdown of SETDB1 is shown in a Western blot below. Each transfection and luciferase assay was repeated at least three times.