Workflow of studies and summary of findings. By using a combination of RNA-Seq, genotyping, and ex vivo drug sensitivity studies, Lavallée and colleagues identified a gene signature of JAK-STAT pathway activation in patients with biallelic CEBPA mutations, which corresponds with enrichment of secondary mutations in JAK-STAT regulating genes, most notably CSF3R, as well as uniform hypersensitivity to JAK kinase inhibitors. Maxson et al performed sequencing on a large cohort of pediatric AML cases with validation of variants in cell transformation assays. They found CSF3R mutations to be higher in this pediatric cohort than in any adult AML cohorts and, consistent with the findings of Lavallée et al, found a significant enrichment of CSF3R mutations within the CEBPA mutated subset.