Gfi-1B knock-down delays acquisition of GPA in CD36⁺ cells. (A) Control of transduction efficiency in primary cells. CD34⁺ from PB (n = 3) were cultured during 5 to 6 days in serum-free medium with EPO, SCF, IL3, and DXM. Fluorescein-labeled nonrelevant siRNA were electroporated day 6 after the beginning of the culture. The percentage of fluorescein-positive cells was determined before (left) and the day after (right) electroporation. (B) CD34⁺ from CB (n = 3) or PB (n = 1) were cultured in the presence of EPO, SCF, IL3, and DXM during 5 to 6 days, then electroporated with the Gfi-1B–specific siRNA (siRNA) or the antisense strand alone (AS) as control. Cells were then cultured in presence of EPO and SCF. After 48 hours, GPA expression level was determined by flow cytometry (antisense versus siRNA: P = .047, n = 4). Data are expressed as mean ± SD. (C) Flow cytometry analysis of one representative experiment, showing CD36/GPA expression (i) before electroporation, (ii) 48 hours after electroporation with the antisense strand alone, (iii) 48 hours after electroporation with the Gfi-1B–specific siRNA.