The invention provides conjugates, comprising an organ, tissue or tumor cell homing molecule linked to a moiety. Such a moiety can be, for example, an oligonucleotide, small interfering RNA, gene, virus, protein, pharmaceutical or detectable agent. In addition the invention provides methods to diagnose or treat neuronal or neuromuscular disease, or a pathology of the brain, or a tumor of neuronal or neuroectodermal origin, by administrating to a subject having or suspected of having a pathology a molecule or conjugate that homes to, binds to and is taken up by the brain cells or neuronal cells, or by the tumor cells of neuronal or neuroectodermal origin. The invention also provides a method of identifying and measuring neurite growth in neuronal cells.
