NFKB1 and mantle cell lymphoma: The BIRC3 (RNF49) is also frequently mutated in 6–10% of patients with mantle cell lymphoma (MCL), a mature CD5+ B-cell neoplasm.102,103 The loss-of-function mutations in BIRC3 release NIK from the inhibition, which results in NIK-NF-κB activation, consequently contributing to the aggressive behavior of MCL.