ATF2 and breast cancer: The phenotypic measurements indicative of malignancy are supported by results from Gene Set Enrichment Analysis (GSEA), which show that genes with decreased expression in soft-selected cells were negatively enriched in oncogenic gene set signatures, such as genes up-regulated in primary epithelial breast cancer cells by overexpression of beta-catenin [CTNNB1, Normalized Enrichment Score (NES): −1.75], genes up-regulated by ATF2 (NES: −1.65) and genes up-regulated in breast cancer cell line MCF7 by overexpression of activated MEK1 protein kinase (MAP2K1, NES: −1.54) (SI Appendix, Fig. S3D).