JAG1 and leukemia: In solid tumors, JAG1 play a role in the promotion of cancer stem cell phenotype by promoting both pro-angiogenic and angiocrine functions in ECs 49, 50 Our findings provide strong rationale for future studies that explore the potential of targeting endothelial JAG1 to suppress leukemia cell survival and promote residual hematopoiesis in T-ALL patients.