MAP2K1 and cancer: Many human cancers contain activating mutations in genes encoding the fundamental signaling cascade constituted of receptor tyrosine kinases, including epidermal growth factor receptor (EGFR), small GTPase Ras (RAS), v-Raf murine sarcoma viral oncogene homolog B (BRAF), Raf-1 proto-oncogene (CRAF), and the mitogen-activated protein kinase kinases (MEK) 1 and/or 2 [1].