RAF1 and fibrosarcoma: Importantly, the activation of oncogenic signaling pathways, such as phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK, also known as rat sarcoma (Ras)–rapidly accelerated fibrosarcoma (Raf)–MEK)/extracellular signal-regulated kinase (ERK), can in cancer cells lead to the induction of vascular endothelial growth factor-A (VEGF-A), one of the most potent proangiogenic factors [67].