Effect of proteasome inhibition on SRC transduction. CD34⁺ cells were transduced with LV-GFP without any stimulation (–cyt), in the presence of 0.7 μM MG132 (–cyt MG), in the presence of cytokines (+cyt), or in the presence of both cytokines and 0.7 μM MG132 (+cyt MG) and transplanted into NOD/SCID mice. Six weeks after transplantation, mouse BM was analyzed by FACS (A) or by quantitative real-time PCR (B-C). (A) Percentage of GFP-positive cells in the human graft. (B) Number of LV integrated copies per human cell. (C) Percentage of human engraftment, calculated as the ratio between human and total (human + murine) DNA. Each dot represents a mouse; for each group, the average (—) is shown. (D) FACS analysis of a mouse undergoing transplantation with cells transduced in the presence of cytokines and MG132 and carrying 34 LV copies per cell; multilineage repopulation is shown by a similar percentage of GFP-positive cells in all the indicated lineages. Percentages were calculated within the gated populations. Human engraftment level was 15%.