This invention relates to a novel target for production of immune and non-immune based therapeutics and for disease diagnosis. More particularly, the invention provides therapeutic antibodies against VSIG1, ILDR1, LOC253012, AI216611, C1ORF32 or FXYD3 antigens, which are predicted co-stimulatory family members and which are differentially expressed in cancers including, lung cancer, ovarian cancer, and colon cancer, and diagnostic and therapeutic usages. The use of these antibodies for modulating B7 costimulation and related therapies such as the treatment of autoimmunity are also provided. This invention further relates to the discovery of extracellular domains of VSIG1 and its variants, FXYD3 and its variants, ILDR1 and its variants, LOC253012 and its variants, AI216611 and its variants, and C1ORF32 and its variants which are suitable targets for immunotherapy, cancer therapy, and drug development.