Retrovirus binding to CD34⁺CD38⁺ and CD34⁺ CD38⁻ cells from adult BM. (A) Cells isolated from a Cell Pro CD34 column were incubated with a virus containing medium and stained with anti–CD34 PECy5 for gating and anti–CD38-PE MoAb and isotype-FITC Ab. (B) Cells incubated as above with FITC-conjugated 83A25 MoAb (anti-mouse retrovirus gp70).