The inhibition of NPM-ALK abrogated the ATIC activity in ALCL cells. The enzymatic activity of ATIC, G6PD, and ODC was measured in ALK⁺ (TS, SU-DHL1, JB-6) and ALK⁻ (Mac-1) lymphoblastoid cell lines after treatment with a specific ALK inhibitor, as described in “Measurement of AICAR-FT/IMP-CHase activity.”