For instance, the PKI sorafenib inhibits the kinases RAF, BRAF, FLT3, VEGFR 1–3, PDGFR, c-KIT and RET and significantly improves progression-free survival compared with placebo in patients with progressive radioactive iodine-refractory differentiated thyroid cancer (21). This evidence concerns the gene PDGFRB and differentiated thyroid carcinoma.