Oncogenic CALR mutant C-terminus mediates dual binding to the thrombopoietin receptor triggering complex dimerization and activation

In myeloproliferative neoplasms, frameshift mutants of calreticulin turn into rogue cytokines by inducing constitutive activation of the Thrombopoietin Receptor (TpoR). Here, the authors define how mutant calreticulin acquires specificity for TpoR binding and triggers its constitutive activation.