MARIMO cells harbor a CALR mutation but are not dependent on JAK2/STAT5 signaling

Mutations in calreticulin ( CALR ) were recently described to be present in the majority of patients with a JAK2 -unmutated myeloproliferative neoplasm (MPN). 1 , 2 This discovery has had rapid clinical impact, and testing for CALR has been embedded in national and international diagnostic guidelines. 3 , 4 , 5 However, a human MPN-derived cell line harboring a CALR mutation has not been reported and the mechanisms by which mutated- CALR results in an MPN remain unclear.