RANBP2 and familial pancreatic carcinoma: On the other hand, motor-independent and disparate functions may be associated also with Ran-GTP-independent subdomains of other Ran GTPase-binding domains of RanBP2, such RBD4, which is known to associate with M-opsin, and where the mutation, M2965I, in a non-conserved subdomain, is found in pancreatic cancers (figure 7b) [72].