Chimerism after busulfan. (A) PBL EGFP chimerism (mean ± SEM) in 5 female B6 mice after recipient pretreatment with busulfan (BU, 2 × 10 mg/kg) followed by transplantation (15 × 10⁶ BMCs) from B6-EGFP.Tg (•) or B6-Ly5.1 (▴) donor mice. (B) EGFP chimerism (mean ± SEM) in male B6 recipients pretreated with saline (4 mice, ▴) or busulfan (2 × 10 mg/kg) (5 mice, •) followed by transplantation (15 × 10⁶ BMCs) from B6-EGFP.Tg donor mice.