Figure 1. Negative selection shRNA screening approaches: single-well format versus pooled libraries.

(A) In single-well arrays, shRNAs are transduced at 1 per well. Negative effect on growth and survival is evaluated individually by direct comparison of corresponding wells in different plates containing Kras wild-type (reference) and Kras mutant cells. (B) Pooled screens are conducted by infecting Kras wild-type (reference) and Kras mutant cells with an shRNA library. The cell populations are then selected either in vitro or in vivo, resulting in shRNAs with unfavorable effects on viability being depleted from the pool of cells. The depleted shRNAs are then identified through bar code tags.