NT-Y723F behaves similarly to wild-type NUP98-TOP1 to induce an in vitro and in vivo proliferative advantage. (A) NT-Y723F induces an increase in the proportion of transduced (GFP⁺) BM cells in liquid cultures similar to that observed for NUP98-TOP1. Graph is representative of 2 independent experiments. Values are mean ± SD of single experiment plated in triplicate. Inset, cytospin preparation taken at day 28. Inset magnification, × 100. (B) Frequency of day 12 spleen colonies obtained immediately after FACS sorting (day 0; left) or following 8 days of liquid culture (day 8; right) (mean ± SD; n > 2). Inset, representative pictures of day 12 spleens following injection of transduced cells cultured for 8 days. GFP CTL spleen was derived from a culture initiated with 2 × 10⁴ cells; in contrast both NUP98-TOP1 and NT-Y723F gave rise to enlarged spleen from only 500 input cells. (C) Schematic representation of NUP98-TOP1 mutants used in this study. (D) Fold increase in the proportion of GFP⁺ cells in liquid culture measured 4 weeks after culture initiation. Representative graph of n = 2 independent experiments with each sample plated in triplicate (Avg ± SD).