Novel LZAP Binding Protein (NLBP)

NLBP and LZAP colocalized in the cytoplasm. Both proteins were subject to ubiquitination, and they appeared to stabilize each other against ubiquitination and degradation via the proteasome.

Domain analysis revealed that an N-terminal region of NLBP and a central region of LZAP were required for the interaction. Knockdown of either NLBP or LZAP via small interfering RNA increased expression of MMP9 and the invasiveness of U2OS cells. Western blot analysis detected reduced levels of LZAP and NLBP in several invasive hepatocellular carcinoma cell lines, but not in a noninvasive cell line. NLBP inhibited the NF-kappa-B signaling pathway.