In one aspect, the present invention provides isolated nucleic acid molecules that encode a CAN-1 polypeptide, or an STG polypeptide. In another aspect, the present invention also provides isolated STG polypeptides, isolated CAN-1 polypeptides, and isolated SEEK-1 polypeptides. In another aspect, the present invention provides isolated antibodies that bind specifically to a CAN-1, SEEK-1 or STG polypeptide. In another aspect, the present invention provides methods of diagnosing or predicting the susceptibility to psoriasis of an individual. In another aspect, the present invention provides methods for ameliorating the symptoms and/or progression of psoriasis.