Leucine repeat adapter protein 25 (Fam89b)

Negatively regulates TGF-beta-induced signaling; in collaboration with SKI prevents the translocation of SMAD2 in the nucleus to the cytoplasm in response to TGF-beta (PubMed:12646588). Acts as an adapter which mediates the specific recognition of LIMK1 by CDC42BPA and CDC42BPB from the lamellipodia.

LRAP25-mediated CDC42BPA/CDC42BPB targeting to LIMK1 and the lamellipodium results in LIMK1 activation and the subsequent phosphorylation of CFL1 that's important for lamellipodial F- actin regulation (PubMed:25107909). .