To assess if ATF4 regulates JAG1 via the CRE binding site on the promoter region of JAG1 in the ECs (Fig. 3A) and if this regulation is influenced by T-ALL development, we performed chromatin immunoprecipitation (ChIP) in ECs co-cultured with WT or ICN1 cells. This evidence concerns the gene ATF4 and acute lymphoblastic leukemia.