CALR and myeloproliferative disorder: In line with these results, we show that treatment with the JAK2 inhibitor ruxolitinib or the BET‐degrader dBET6, but not BET inhibitor JQ1, leads to downregulation of PD‐L1 expression in CD34+CD45dimCD38− stem cells in JAK2‐V617F positive MPN patients, while all three drugs exerted inhibitory effects in JAK2 and CALR‐mutated cell lines.