ELK1 and esophageal squamous cell carcinoma: Especially mentioned, we determined the effect of CST1 on the phosphorylation of CREB other than ELK1 in ESCC cells, although either of which is the key downstream effector of MEK/ERK, and the MEK/ERK/CREB pathway has been demonstrated its role on regulating cell malignant biological behaviors as well as EMT-related process in many malignancies [19, 20] Therefore, it is reasonable to deduce that CST1 might promote the migration and invasion of ESCC cells by activating MEK/ERK/CREB pathway.