KITLG and plexiform neurofibroma: Neoplastic SCs also secreted cytokines, such as stem cell factor (SCF) and colony-stimulating factor 1 (CSF1); such factors were proposed to act in a “cytokine-cytokine receptor” manner, recruiting immune cells such as mast cells and macrophages, both of which secrete transforming growth factor-β (TGF-β) to active neurofibroma-associated fibroblasts for ECM remodeling [51].