EXPERIMENTAL MODEL AND SUBJECT DETAILS

293FT, NIH 3T3, Phoenix-Eco, RL95–2, and RAS-deficient MEFs were cultured in DMEM. H358 cells were cultured in RPMI, T24 cells in McCoy’s 5a, and SW480 in L-15. All media was supplemented with 10% fetal bovine serum (FBS), 2 mM L-glutamine, and 1% penicillin/streptomycin. MCF10A cells were cultured in DMEM/F12 supplemented with 5% horse serum, 0.5 μg/mL hydrocortisone, 20 ng/mL EGF, 100 ng/mL cholera toxin, 10 μg/mL insulin, and 1% penicillin/streptomycin. All cell lines were cultured at 37°C under 5% CO₂ except for SW480 cells, which were cultured at 37°C under atmospheric conditions. Ras-deficient MEFs were sequenced by the provider (NCI-Ras Initiative) to confirm loss of endogenous Ras and integration of the transgene.