Ruxolitinib (FDA approved, known as a dual inhibitor of JAK1/JAK2, named hereafter JAKi) [21] is one of the most promising drugs as it efficiently reduced the activation of IL7/IL7R signaling through a significant reduction of STAT5 phosphorylation (Fig. S3C) and STAT5 target gene expression (e.g. BCL2) in Zeb2Tg ETP-ALL (Fig. S3C). Here, JAK1 is linked to acute lymphoblastic leukemia.