ATF4 and acute myeloid leukemia: FAO inhibition by etomoxir, an inhibitor of the FAO key rate-limiting enzyme carnitine O-palmitoyltransferase 1 (CPT1), disrupted metabolic homeostasis, increased ROS production, and subsequently induced expression of the integrated stress response (ISR) mediator activating transcription factor 4 (ATF4) in AML cells (84).