The mostly diploid SUM159 human breast carcinoma cells37 (link) were provided by J. Brugge; they were grown at 37 °C and 5% CO2 in DMEM/F-12/GlutaMAX (GIBCO), supplemented with 5% fetal bovine serum (FBS, Atlanta Biologicals), 100 U/ml penicillin and streptomycin (VWR International), 1 μg/ml hydrocortisone (Sigma-Aldrich), 5 μg/ml insulin (Sigma-Aldrich), and 10 mM HEPES (Mediatech), pH 7.4. The de-identified human dermal fibroblasts from a control culture (PHL336)38 (link),39 (link) were a gift from P. De Camilli. COS-7 cells were obtained from The American Type Culture Collection (ATCC). COS-7 cells and human dermal fibroblasts were grown at 37 °C and 5% CO2 in DMEM (GIBCO) supplemented with 10% FBS (Atlanta Biologicals), 100 U/ml penicillin and streptomycin (VWR International). All cells were routinely verified to be mycoplasma free using a PCR-based assay.