NQO1 and acute promyelocytic leukemia: Two human hematopoietic cell lines, HL-60 (promyelocytic leukemia) and Raji (Burkitt’s lymphoma), both show similar, substantial reduction of NQO1 transcript levels [45]; phenotypically, however, a complete loss of NQO1 activity was only evident in Raji, while the HL-60 cells expressed a low level of enzyme activity.