USB1 ^P44L expression does not block in vitro neutrophil differentiation of CD34 ⁺ human cells. (A) In vitro liquid culture differentiation (SCF, G-CSF) of CD34⁺ representative images at day 8. CD15⁺/CD11b⁺ plots are gated on GFP⁺ (up) and GFP⁻ (down) CD14⁻ cells for the indicated USB1 variants. (B) Percentage of CD14⁻CD15⁺CD11b⁺ cells either GFP⁺ (left) or GFP⁻ (right). Bars and error bars are the averages of the percentage of the indicated populations and SD from at least two independent experiments (n ≥ 2). (C) Representative MGG staining images of sorted GFP⁺ cells showing the characteristic morphology of neutrophils (day 14, n = 3). Scale bar = 20 µm. (D) CFU potential of myeloid differentiation in GFP⁺ sorted cells at 2.5 days after transduction (n = 3). Ordinary one-way ANOVA statistical analysis was performed. *P < 0.05. Nonsignificant differences were not annotated. CFU, colony-forming unit; EV, empty vector.