Proposed mechanism of IMiD-induced CG up-regulation. Treatment of hematopoietic progenitors leads to a down-regulation of PU.1, which results in a maturational block of neutrophil granulocytes with peripheral blood neutropenia. The block of maturation leads to an accumulation of neutrophil promyelocytes. The azurophilic granules of promyelocytes store high amounts of serine proteases, such as CG and NE2. Subsequently, levels of CG and NE2 are up-regulated, contributing to the increased risk of VTE.