Cytokine receptor-like factor 2 is a protein that in humans is encoded by the CRLF2 gene. It forms a ternary signaling complex with TSLP and interleukin-7 receptor-α, capable of stimulating cell proliferation through activation of STAT3, STAT5 and JAK2 pathways and is implicated in the development of the hematopoietic system. Rearrangement of this gene with immunoglobulin heavy chain gene (IGH), or with P2Y purinoceptor 8 gene (P2RY8) is associated with B-progenitor- and Down syndrome- acute lymphoblastic leukemia (ALL).