Facilitates the ubiquitin-independent proteasomal degradation of stimulus-induced transcription factors such as FOSB, EGR1, NR4A1, and IRF4 to the proteasome for degradation (PubMed:37616343). Promotes also the degradation of other substrates such as CBX4 (By similarity). Plays a role in inhibiting the activity of glucokinase GCK and both glucose-induced and basal insulin secretion.