Through the activation of JUN and AP-1-mediated transcription, may regulate apoptosis. Interacts with COPS5; regulates the phosphorylation of JUN and the transcriptional activity of AP-1. Interacts with RYBP; may prevent the ubiquitin-mediated proteasomal degradation of FANK1. Detected in germinal vesicle (GV) stage oocytes and in embryos up to the 8-cell stage, but not in morula or blastocysts. The fibronectin type-III domain mediates interaction with COPS5 and RYBP. Polyubiquitinated. Polyubiquitination leads to proteasomal degradation.