shRNA specificity and activity was maintained in transferred expression cassettes. Each shRNA expression plasmid was co-transfected into HEK293a cells with two reporters; the corresponding target-specific GFP fusion and a non-specific AsRed-1 fusion. All shRNA were separately tested with the 9 reporters individually matched to each shRNA (n.b. two LTR shRNA, #0 and #1, shared targeted the same reporter). Target-specific fluorescence levels were normalized to non-specific effects measured with the AsRed-1 fusion, and presented relative to the fluorescence levels from the corresponding empty expression cassette plasmid (value set at 100%; not shown). A key to the reference #s used in the original study is given below the 0 - 9 #s used here for cross-reference. Off-scale values (> 100%, i.e. no activity) are indicated by open circles without error bars, and with text labels where appropriate. Error bars are 95% Confidence Intervals (CI) from 3 independently repeated experiments.