MAP2K7 and cancer: To gain some insight into the mechanisms regulating cellular senescence in epithelial cells, which are at the origin of most cancers, we characterized the transcriptome of immortalized human mammary epithelial cells expressing a fused inducible (by 4-OHT) MEK:ER oncogene (HMEC-MEK), a model of oncogene-induced senescence (OIS) that we have described previously17–19.