The assembly of microtubules, an essential step in neurogenesis, is modulated by the family of microtubule-associated proteins (MAPs). These proteins have been divided into 2 main groups by molecular mass, high molecular weight MAPs, which include MAP1A, MAP1B , and MAP2 , and another group of intermediate-sized proteins, which include the abundant tau MAPs. MAP1A is the largest brain MAP and expressed prominently in dendrites and to a lesser extent in cell bodies and axons . This protein is involved in differentiation of axons and dendrites as well as maintenance of the microtubule cytoskeleton in mature neurons.