ATF4 and acute myeloid leukemia: AML cells that are co-cultured with adipocytes also overexpress FABP4, a lipid chaperone, and knock down of this chaperone in AML cells prolonged survival in in vivo models.343,344 While studies regarding FAO and AML metabolic homeostasis are limited, it is well understood that FAO inhibition increases ROS production, induces apoptosis, and overcomes resistance to conventional AML chemotherapeutics via induction of the ISR mediator, ATF4.341,345 A key rate-limiting enzyme of FAO is carnitine O-palmitoyltransferase 1, which has several isoforms (CPT1A, CPT1B, and CPT1C).