Mechanistic studies using a new vascular tumor cell line derived from Tsc1iΔEC mice showed that blocking autophagy by depletion of FIP200, as well as knockout of two other autophagy genes Atg5 or Atg7, significantly inhibited vascular tumor cell proliferation in vitro and tumorigenicity in mice transplant assays. This evidence concerns the gene ATG5 and vascular neoplasm.