For example, tumors develop resistance to vemurafenib through the following mechanisms: tumor cells begin to overexpress PDGFR-B [47], N-ras mutation reactivates the normal B-Raf pathway [47], tumors induce feedback activation of the EGF receptor [48], and stromal cells around tumor secrete hepatocyte growth factor [49]. This evidence concerns the gene PDGFRB and neoplasm.