A recent large-scale genomic evolution study of patients with breast cancer metastasis and local relapse revealed that metastases had a higher mutation burden than primary tumors, including inactivation of the SWItch/sucrose nonfermentable and Janus kinase 2-signal transducer and activator of transcription 3 (JAK2-STAT3) pathways [23]. Here, JAK2 is linked to breast cancer.