CSF1 and myeloproliferative neoplasm: The mentioned changes may explain the drop in PD-L1 expression in the fibrotic phase of MPN because The Cancer Genome Atlas (TCGA) data documents a strong positive association between M-CSF, CXCR3 expression, and PD-L1 expression in another myeloid malignancy-acute myeloid leukemia (Fig. 3).