FN1 and acute basophilic leukemia: The adhesion of mast cells and basophils to extracellular matrix (ECM) proteins such as fibronectin (FN), collagen (CO), laminin (LN) or vitronectin (VN) for instance has been shown to play an important role in enhancing degranulation of rat basophil leukaemia RBL-2H3 cells [14–16].