For examples, the CUEDC protein, ERAD E3 gp78, is a regulator of liver homeostasis and a tumour suppressor in liver, and its CUE domain interacts with ubiquitin and diubiquitin and functions to facilitate substrate binding and processivity in ubiquitination (Liu et al., 2012a; Zhang et al., 2015); another CUEDC protein, CUEDC2, suppresses glioma tumorigenicity by inhibiting the activation of STAT3 and NF‐κB, and its CUE domain is essential for functional interactions with both monoubiquitin and polyubiquitin (Li et al., 2017). This evidence concerns the gene STAT3 and central nervous system cancer.