In addition, Nfkb1-deficient leukemic cells presented a cell surface marker phenotype (expression of variable levels of CD4, CD8, CD24, CD25, and TCRβ/CD3ε) similar to that of Nfkb1-proficient cells (data not shown) and characteristic of transgenic TEL-JAK2 leukemia [21], [25]. This evidence concerns the gene JAK2 and leukemia.