The present invention relates to neukinase, a downstream protein kinase in the neuregulin signaling pathway. In certain aspects, the present invention provides isolated neukinase-encoding nucleic acids, neukinase polypeptides, oligonucleotides that hybridize to neukinase nucleic acids, and expression vectors containing neukinase-encoding sequences. The present invention further provides isolated host cells, antibodies, transgenic non-human animals, compositions, and kits relating to neukinase. In other aspects, the present invention further provides methods of identifying predisposition to cardiac dysfunction, methods of detecting the presence of neukinase, neukinase nucleic acid, methods of screening for agents which affect neukinase activity, and methods of modulating neukinase activity.