ELK1 and neoplasm: ELK1, as a transcription factor, is phosphorylated through activating the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathways and translocates to the nucleus, leading to the regulation of downstream targets, including a proto-oncogene c-fos [6,7], as well as matrix metalloproteinases (MMPs) [8,9] that contribute to tumor cell invasion.