Knockdown of FASN inhibits OS cell metastasis in nude mice. (A) X-ray of xenograft tumor in nude mouse. (B and C) Xenograft tumors were anatomized and (D) lung tissues of sacrificed mice were cut into sections, stained with hematoxylin and eosin and visualized under a microscope (magnification, ×400). Metastasized tumor cells (black arrow) were identified. (E) Incidence of spontaneous metastasis was significantly reduced (P<0.001) in Lv-shFASN-treated mice (8.33%) compared with that in the Lv-negative group (25.00%). Lv, Lentivirus vector; sh, small hairpin; FASN, fatty acid synthase; OS, osteosarcoma; Lv-negative, control group.