JAK1 and acute lymphoblastic leukemia: Pre‐B NRASG12D ALL cells in the absence of IL‐7 showed high expression levels of NRASG12D, increased phosphorylation of ERK1/2 and a consecutive induction of MAPK negative regulators (DUSP6 and ETV5) along with reduced phosphorylation of the downstream effectors JAK1 and STAT5.