NFKB1 and schizophrenia: However, previous postmortem findings by Rubio et al. 16 showed elevated levels of K63-linked and decreased levels of K48-linked poly-ubiquitinated proteins in schizophrenia relative to controls, implicating signaling pathway modulation, NF-kB activation, and/or DNA repair, rather than proteasomal degradation, may be perturbed in schizophrenia56.