p2-siRNA is able to produce two different siRNAs targeting different regions of TRAF6 mRNA or two copies of the same siRNA to increase the efficiency of gene silencing. a) Construction and schematic diagram of Vec2, Vec6, Vec26 and Vec66. In addition, schematic location of sequence Si6A and Si6 are also depicted. UTR: untranslated region. Sequence of Si6 and Si6A are shown in additional files (see Additional file 2). b) Western analysis showing that Vec66 exerts higher inhibitory effect on TRAF6 expression than Vec6. C: uninfected BMMs control. Actin was probed as loading control. The expression levels of TRAF proteins were normalized to that of actin. These Western blot assays were independently repeated three times and a representative data is shown. c) Western analysis showing that Vec26 exerts higher inhibitory effect on TRAF6 expression than Vec2 or Vec6. C: uninfected BMMs control. Vec2C: control containing the scrambled Si6A sequence. Vec6C: control containing the scrambled Si6 sequence.