SLAMF7 and myeloproliferative neoplasm: Several studies focusing on monocytes have revealed that abnormal monocytes may play a significant role in MPN progression through pro-angiogenesis by expressing Tie2 [20,21], pro-fibrosis by expressing SLAMF7 [22], pro-tumor activity via cytokine secretion such as TNF-α [23], and inhibiting T cell function through increased expression of PDL1 [24,25], as well as modulating the tumor microenvironment by differentiating into tumor-associated macrophages, etc. [26].