Based on the remarkable effect of CST1 in upregulating the phosphorylation of MEK/1/2/ERK1/2 observed in our pilot study30 and the potential of the activated MEK/ERK pathway to enhance the activity of the cellular mitochondrial respiratory chain41, we deduced that there may be a crosstalk between mitochondrial OXPHOS and the MEK/ERK pathway in ESCC cells with CST1 overexpression. The gene discussed is MAP2K7; the disease is esophageal squamous cell carcinoma.