Pooled shRNA screens with mouse retroviral shRNA epi-library. (A) Schematic map of the pMLS vector. (B) Categories of chromatin-associated factors represented in the mouse retroviral shRNA epi-library. (C) Screening strategy. Mouse primary MLL-AF9 AML cells or c-Kit–enriched mouse BM cells were transduced with the epi-library. Two days after transduction, GFP+ cells were FACS sorted, and cells were harvested at day 0 and day 14 for genomic DNA. shRNA hairpins were amplified by PCR and submitted for sequencing. (D) Screening result in MLL-AF9 AML cells. Data are presented as the ratio of normalized read number at day 14 to normalized read number at day 0 for each shRNA in the library. The result is an average of 2 replicates. Positive controls: orange; negative (nontargeting): green; shRNAs targeting Jmjd1c: blue. Inset shows correlation of normalized reads per shRNA between 2 replicates. (E) Screening result in c-Kit–enriched BM cells. Two independent experiments are presented. Control and Jmjd1c shRNAs are marked as in (D).