c-kit gene expression in human hematopoietic cells transduced with the TRIP vectors. (A) Quantitative measurement of c-kit mRNA levels in CD34⁺ cells after transduction (day 0, CD34⁺ cells) and in transduced CD34+CD36^+/- cells sorted after 3 days of serum-free culture in the presence of SCF, IL-3, and IL-6. Results of TRIP-TAL1/ΔbTAL1-transduced cells are expressed as a proportion of the results obtained with the EGFP⁺ cells. Each measurement was made 3 times. (B) c-KIT protein levels in human hematopoietic cells recovered after transduction (day 0; all cells are CD34⁺) and 5 days after the end of the transduction, following a culture period in conditions described in “Materials and methods.” Blot was reprobed with the anti-c-KIT Ab (clone C19, TEBU) after a first probing with the 2TL136 anti-TAL1 Ab (Figure 1D). All data are representative of 2 experiments.