STK11 and neoplasm: Given the evidence that tumor cells are Lkb1-positive and strict EYFP expression in tumor ECs (identified by positive staining for vWF [vWF+]) in the lineage-tracking mice (Stk11ec (EYFP)−/−), we concluded a non-cell-autonomous effect of EC Stk11 deficiency on tumorigenesis or tumor suppression.