TGM2 and cancer: Though TG2 was shown to crosslink IκB [69], in cancer cells either extracellular TG2 induces the noncanonical pathway of NF-κB activation by activating IκB kinase [70], or cytoplasmic TG2 directly interacts with IκB [71], which might be affected by a PKA-dependent serine-216 phosphorylation of TG2 [67].