AES enhances proliferation and self-renewal in hematopoietic progenitor cells. Colony formation of murine primary BM cells retrovirally transduced with AES or empty control vector. (A) Higher numbers of relative colonies after AES overexpression. Bars represent relative colony numbers of 3 experiments. (B) The increase in the colony count was associated with an increased fraction of immature colonies (results and SE are shown). *Statistical significance at P < .05. White bars represent empty vector control; and black bars AES overexpression. (C) AES-transduced murine BM cells were serially plated twice. The results of 4 rounds of replating with SE are shown. *Statistical significance at P < .05. White bars represent empty vector control; and black bars AES overexpression. (D) AES-transduced murine BM cells were analyzed for AES expression. (E) CFU-S d12 assays were performed with AES-overexpressing, transduced BM cells and control cells. Three of 5 spleens of mice transplanted with AES-overexpressing cells showed a strong increase in macroscopic CFU-S numbers. These spleens and representative controls are shown. (F) A second set of CFU-S d12 assays with AES-overexpressing, transduced BM cells and control cells was performed, and microscopic colonies were counted. Data are mean plus or minus SD. The difference was statistically significant (P = .001). (G) Protein lysates of spleen tissue with colonies were analyzed for c-myc expression by Western blot analysis. (H) Primary BM cells from GRG5 KO-mice and wt-mice were transduced with AML1/ETO and serially transplated. The results of 6 rounds of replating are shown. *Statistical significance at P < .01 (paired t test).