BTRC and esophageal squamous cell carcinoma: NRF2 protein expression is known to be regulated by the E3-ligases KEAP1 [18] or β-TrCP [19]; however, the dysfunction of the two E3-ligases were not common in ESCC, and no significant correlation was found between CCRT response and the expressions of both KEAP1 and β-TrCP [20, 21].