The reason is that sorafenib inhibits the proliferation of HCC cells and neovascularization by inactivating the Ras/Raf/MEK/ERK pathway but simultaneously activates the PI3K/Akt pathway and inhibits the expression of the tumor suppressor phosphatidylinositol esterase and tension protein homolog (PTEN). The gene discussed is PTEN; the disease is hepatocellular carcinoma.