NFKB1 and esophageal squamous cell carcinoma: PIWIL2 induced activation of IKK then induces phosphorylation of IκB and releasing of NF-κB for nuclear translocation and apoptosis inhibition (Fig. 4), suggesting that PIWIL2 can repress apoptosis in ESCC cells by activating the classic IKK/IκB/NF-κB pathway.