Although the outcome of targeted Npn-2 RNAi in the chick spinal cord indicates that the ectopic motor neuron phenotype could be a cell-autonomous effect, it remained a possibility that a reduced prevalence of BC cells at the MEP might contribute to the phenotype in Npn-2 null mice since the absence of Npn-2 leads to aberrant neural crest migration [22]. This evidence concerns the gene NRP2 and breast cancer.