This invention provides a fusion protein comprising a signal peptide, EGF repeats 1-X of the extracellular domain of human Notch3 receptor protein wherein X is any integer from 12 to 34, and an Fc portion of an antibody bound thereto. This invention also provides a method for treating a subject having a tumor, a method for inhibiting angiogenesis in a subject, a method for treating a subject having ovarian cancer, and a method for treating a subject having a metabolic disorder, comprising administering to the subject an amount of the above fusion protein effective to treat the subject. This invention further provides uses of the above fusion protein for the preparation of a pharmaceutical composition for the treatment of a subject having a tumor, for inhibiting angiogenesis in a subject, for treating a subject having ovarian cancer, and for treating a subject having a metabolic disorder.