NFKB1 and esophageal cancer: PELI1, a NIK E3 ubiquitin ligase, mediates the degradation of NIK and then suppresses the activation of the IR-stimulated NF-κB, causing the downregulation of Bcl-XL, thereby promoting the apoptosis of esophageal cancer cells induced by radiotherapy [119], indicating that activation of the NIK/NF-κB pathway could promote radioresistance by inhibiting apoptosis.