The invention provides isolated nucleic acids that encode LCP, including two isoforms, and fragments thereof, vectors for propagating and expressing LCP nucleic acids, host cells comprising the nucleic acids and vectors of the present invention, proteins, protein fragments, and protein fusions of the novel LCP isoforms, and antibodies thereto. The invention further provides transgenic cells and non-human organisms comprising human LCP nucleic acids, and transgenic cells and non-human organisms with targeted disruption of the endogenous orthologue of the human LCP gene. The invention further provides pharmaceutical formulations of the nucleic acids, proteins, and antibodies of the present invention, and diagnostic, investigational, and therapeutic methods based on the LCP nucleic acids, proteins, and antibodies of the present invention.