NF1 and cancer: These endothelial cells promoted cancer cell proliferation by secreting platelet-derived growth factor subunit B (PDGFB), which was stimulated by cancer cell-secreted vascular endothelial growth factor (VEGF), fibroblast growth factor 12 (FGF12), pleiotrophin (PTN) and neurofibromin 1 (NF1) [60].