NGFR and leukemia: We confirmed accelerated depletion of three different HOXB3 shRNAs as compared to nonsilencing controls in singleton transduction experiments by flow cytometry using NGFR-tagged viral shRNA constructs in the same primary NLTB leukemia as used for the 59-plex shRNA screen, and also in a second, independent primary NLTB leukemia (Fig. 8c).