Based on limited published evidence, RMND5B is a core component of the CTLH E3 ubiquitin-protein ligase complex that mediates selective ubiquitination and proteasomal degradation of target proteins including the transcription factor HBP1 1. The complex requires both MAEA and RMND5A for catalytic activity, which is essential for normal cell proliferation 1. RMND5B functions in the cytosol and nucleus, accepting ubiquitin from UBE2H to regulate protein degradation. The CTLH complex does not target gluconeogenic enzymes like FBP1 1. Recent evidence demonstrates CTLH complex components regulate non-small cell lung cancer proliferation through proteome remodeling 2.