CALR and essential thrombocythemia: Similarly, MAPK and PI3K pathways seem to be less activated in CALR-mutated ET: these data are consistent with the results obtained by Chachoua et al.15, which have shown that there is a strong synergy between JAK2 and PI3-K inhibitors in restraining the cytokine-independent proliferation of JAK2V617F-positive cells, unlike what occurs in the CALR-mutated cells.