Decreased total plasma bilirubin (milligrams per deciliter) levels in (A) 5-FU–treated HO-1^+/− mice or (B) recipients of HO-1^+/− BM cells. Levels of total plasma bilirubin in HO-1^+/− or HO-1^+/+ mice at day 8 after receiving a single dose of 5-FU (150 mg/kg, intraperitoneally) and in the recipients of 2 × 10⁶ HO-1^+/− or HO-1^+/+ BM cells at day 22 day after BM transplantation. P values were calculated using one-tailed t test.