BCR-ABL1-neg MPN patients frequently carry somatic mutations of Janus kinase 2 (JAK2) tyrosine kinase, with JAK2-V617F identified as the most prevalent variant that induces overactivation of JAK/STAT signaling and its downstream pathways, which is also observed in MPNs driven by other mutations in JAK2, MPL, and CALR (Pasquier et al., 2014). Here, JAK2 is linked to myeloproliferative disorder.