The present invention relates to molecules that are capable of killing cells. The molecules comprise a targeting agent and a channel-forming moiety. The molecules may be polypeptides. The present invention also relates to polynucleotide sequences encoding the polypeptides of the invention. In a preferred embodiment, the channel-forming moiety comprises a colicin and the targeting agent is an antibody. Methods of treatment by administering the molecules of the present invention are also provided.
