KLRK1 and cancer: However, this task might be impeded by platelets, which are small non-nucleated fragments of megakaryocytes that aggregate with fibrin deposits on cancer cells’ surface in a process miming coagulation.459 Additionally, aggregated platelets could transfer MHC I to MHC I-deficient cancer cells, thereby interfering with the missing self-recognition by NK cells.460 In addition to the physical shielding of cancer cells, platelets are the richest source of TGFβ1, downregulating NKG2D in NK cells.461