CRLF2 and acute lymphoblastic leukemia: However, these result in activation of common surface receptor/kinase signalling pathways: predominantly the JAK-STAT class (particularly via CRLF2 rearrangements, such as IGH-CRLF2 and P2RY8-CRLF2, which are seen in more than 40% of Ph-like ALL); less frequently ABL-class (ABL1, ABL2, PDGFRA, PDGFRB, CSF1R); and in smaller numbers RAS signalling (KRAS, NRAS, PTPN11, CBL, NF1) and other pathways (e.g., FLT3, FGFR1, NTRK3) [40,41].