Mouse fibroblast cell lines 3T3 (ATCC CRL-1658) and 3T12 (ATCC CCL-164) and mouse endothelial cell lines MB114 [68] , SVEC4-10 (ATCC CRL-2181), and CD3 [69] were cultured in Dulbecco's Modified Eagle Media (DMEM) supplemented with 5% FBS (Hyclone, Logan, UT), 2 mM L-glutamine, 10 U/mL penicillin, and 10 mg/mL streptomycin sulfate. S11 [20] and S11E tumor cells [22] were cultured in RPMI 1640 medium (Gibco) supplemented with 10% FBS, 50 mM b-mercaptoethanol, 1 mM sodium pyruvate, 2 mM L-glutamine, 10 U/mL penicillin, and 10 mg/mL streptomycin sulfate (complete RPMI). Mouse embryonic fibroblasts were isolated from C57/BL6 mice as previously described [70] and cultured in DMEM supplemented with 10% FBS, 2 mM Lglutamine, 10 U/mL penicillin, 10 mg/mL streptomycin sulfay7te, and 250 ng/mL fungizone. Isolation, characterization, and culture of primary endothelial cells from C57/BL6 mice was done according to previously published methods [71] and is described in Protocol S1, Text S1 and Figure S3A .