Background: MAP1B is one of the founding members of the MAP (microtubule-associated protein) family of proteins involved in microtubule assembly. MAP1B is almost exclusively expressed in the developing brain and is critical for axon formation. MAP1B-null mice exhibit an absence of the corpus collosum and impaired axon development. MAP1B is processed by proteolytic cleavage that leads to the generation of a 300 kDa heavy chain and a 32 kDa LC1 light chain.