JAK2 and juvenile myelomonocytic leukemia: However, mutations which are reported to play a major role in myeloproliferative neoplasms, such as ten-eleven translocation-2 (TET2), runt-related transcription factor 1 isoform (RUNX1), janus kinase 2 (JAK2) V617F [54], and Soc-2 suppressor of clear homolog SHOC2 [55] are not involved in JMML.