HGF and neoplasm: The accumulated genetic/epigenetic changes accompanying evolution of aggressive subtypes of cutaneous SCC are intertwined in a complex signaling landscape emanating from both tumor cells and stromal-derived elements (e.g., hepatocyte growth factor (HGF); epidermal growth factor (EGF); platelet-derived growth factor (PDGF); transforming growth factor-β (TGF-β)) [19–24].