Cell culture

We obtained murine RENCA cells from the American Type Culture Collection (Manassas, VA). We cultured cancer cells in RPMI-1640 medium (Nissui, Tokyo, Japan) supplemented with 10% fetal bovine serum (FBS) (Hyclone, Logan, UT). We cultured mouse lung ECs in endothelial cell basal medium (EBM-2) supplemented with the EGM-2MV Bullet Kit (15% FBS) (CC-3202; Lonza Walkersville Inc., Walkersville, MD). We purchased HUVECs from Lonza Walkersville Inc. and cultured them in EBM-2 supplemented with the EGM-2 Bullet Kit (2% FBS) (CC-3162; Lonza Walkersville Inc). We passaged all cell lines for ≤6 months and they were not further tested or authenticated by the authors. None of the cell lines used in this study was authenticated by the authors. For primary mouse lung ECs, we checked the expression of vascular endothelial markers CD31, ICAM-2, VEGFR2, and VE-cadherin. All cell lines were routinely tested negative for mycoplasma contamination. No commonly misidentified cell lines were used.