Contribution of individual cytokines to enhanced HSPC transduction by LVs. (A) Percentage of GFP-positive cells in suspension culture and colonies (CFC) of CD34⁺ cells transduced with 10⁸ TU/mL LV-GFP without (–cyt) or with the indicated cytokine, added separately (IL-6, SCF, TPO, Flt3L) or all together (+cyt), and with or without (NT [not treated]) 1μM MG132. (B) Mean fluorescence intensity (MFI) of suspension culture cells shown in panel A. One experiment of 2 performed with similar results is shown.