Upon mitogenic stimulation, MAPK signaling activates an array of downstream effectors including the transcription factor MYC, which is associated with genomic instability and progression in multiple cancers (Sears et al, 2000; Prochownik, 2008), and is known to be targeted by MEK1/2 blockade in breast cancer cells (Duncan et al, 2012). Here, MAP2K1 is linked to breast cancer.