Bone marrow infiltration of ALL-11 engrafted mice at day 1 and day 8. Bone marrow infiltration of mice engrafted with ALL-11 empty vector or AKR1C3 cDNA, both of which have GFP reporters. Samples were harvested 24 hours after the first dose of PR-104 (day 1, A) or 24 hours after the second dose of PR-104 (day 8, B) and cells were run on flow cytometry to determine the presence of GFP⁺ and hCD45⁺ cell populations. (C) Immunofluorescence for GFP in the bone marrow of PR-104–treated mice at day 8 shows absence of the GFP reporter in mice inoculated with cells transduced with AKR1C3 cDNA compared with empty vector. (D) Quantitative data showing the percentage of hCD45⁺ cells in n = 8 femurs. Data represent the mean ± SEM. *P < .01; **P ≤ .0005 by unpaired Student t test with Welch correction.