KDR and fibrosarcoma: Autocrine VEGF-VEGFR2 signaling induces an intracytoplasmic signaling cascade that phosphorylates the rat sarcoma virus (Ras)/rapidly accelerated fibrosarcoma (Raf)/extracellular regulated kinase 1/2 (ERK 1/2) and phosphoinositide 3-kinase (PI3K)/AKT proteins [36,37].