Provided is a method for directing differentiation of neural progenitors with a caudal and ventral specification into motor neurons including culturing neural progenitors in a culturing medium including a basic medium supplemented by at least one inhibitor of the Notch signaling pathway whereby the neural progenitors differentiate into postmitotic motor neurons. The resulting motor neurons may be used for drug development, as carriers, e.g. for gene therapy of protein delivery as well as for transplantation for the purpose of treating a motor neuron disease.