Silencing occurs at the LT-HSC level.

LT-HSC were analyzed in an animal that showed no evidence of sustained GFP expression after long-term reconstitution even though the animal was highly donor-reconstituted. Donor hematopoietic stem cells were analyzed for being Ly-5.2⁺ (APC), Sca-1⁺ (Texas Red), lineage marker–negative (Cy5-PE), c-kit⁺ (PE), and GFP⁺ or GFP⁻.