Figure 5

Cassette number and position effects on suppressive activity. Twenty seven control plasmids, each containing a single shRNA expression cassette (shRNA #3) plus 1 or more empty expression cassettes for all possible 2, 3, 4, 5, 6 and 7 cassette plasmids were tested with the fluorescent reporter assay using the matched Pol-1 (1 - 436) reporter across a titrated range of shRNA plasmid amounts from 400 ng to 1 ng. The activity of each combination was calculated as a% of the fluorescence from the corresponding control of same cassette number and ~ length but composed entirely of empty expression cassettes (values set at 100%; not shown). Off-scale values are indicated by open circles.