Microtubule-stabilizing protein that may be involved in the regulation of microtubule dynamics and cytoskeletal organization. May act as a regulator of RAC1 activity through interaction with ARHGEF2 to control lamellipodial formation and cell mobility. Does not seem to have protease activity as it has lost the active site residues (By similarity). Interacts (via domain III) with microtubules. Interacts (via domain II) with ARHGEF2 (via the N-terminal zinc finger). During mitose associated with the mitotic spindle. At telophase colocalized to the midbody spindle. Expressed only in placenta. Belongs to the peptidase C2 family.