Four independent groups in late 2009 and early 2010 have identified that up to 50 % of BCR-ABL1-like ALL cases have dysregulated expression of CRLF2, the gene encoding the cytokine receptor-like 2 factor, also known as thymic stromal lymphopoietin receptor [40–43]. Here, CRLF2 is linked to acute lymphoblastic leukemia.