QPRT and acute lymphoblastic leukemia: According to their different initial genetic background, the two cell lines that we utilized for our study, CCRF-CEM and MDA-MB231, exploit different mechanisms to synthesize NAD+: the T-ALL cell line, CCRF-CEM, was found not to express NAPRT but expressed QPRT, and their resistance phenotype reflected the ability to exploit amino acid catabolism, on the one hand, and an increase in their glycolytic flow and LDHA activity, on the other.