Efficiency of ABCB7 siRNAs. HeLa cells were transfected with 100 pmol of the indicated siRNAs, and the level of ABCB7 mRNA was quantified by real-time RT-PCR. The results are expressed as percentage of the control mock-transfected cells. (A) The siRNAs coded 792, 871, and 1663 were obtained by in vitro transcription and the HeLa cells analyzed 48 hours after transfection. (B) The siRNA 792 was produced by chemical synthesis and used in 2 rounds of transfection, and the cells were analyzed 48 hours after the second transfection. Mean and SD of 4 experiments. Scr indicates scrambled siRNA. *Significant difference (P < .05).