The role of ACVR1 inhibition in anemia-related benefits in myelofibrosis is also supported by the more recent finding that pacritinib, another JAK inhibitor previously described as a JAK2/fms-related receptor tyrosine kinase 3 (FLT3)/interleukin 1 receptor-associated kinase 1 inhibitor, also inhibits ACVR1 and showed retrospective evidence of anemia-related benefits in clinical trial analyses [27,28]. Here, ACVR1 is linked to myelofibrosis.