1. An isolated nucleic acid comprising, encoding polypeptide a nucleotide, comprising aminoacids 21-290 SEQ ID NO: 7. 2. An isolated nucleic acid comprising, encoding polypeptide a nucleotide, comprising aminoacids 1-290 SEQ ID NO: 7. 3. An isolated nucleic acid according to claim 1 or 2, where encoding polypeptide further comprises a Fc-domain Ig. 4. An isolated nucleic acid comprising nucleotides 278-1147 SEQ ID NO: 6 or a sequence complementary to nucleotides 278-1147 SEQ ID NO: 6. 5. An expressing DNA vector, comprising nucleic acid according to claim 1 or 2. 6. An expressing DNA vector, comprising nucleic acid according to claim 4. 7. A host cell comprising the vector according to claim 5 or 6. 8. A polypeptide production method, comprising culturing a host cell according to claim 7 in a cell culture medium and recovering a polypeptide expressed from the vector within said host cell. 9. An isolated polypeptide, comprising amino acids 21-290 SEQ ID NO: 7. 10. Polypeptide comprising polypeptide according to claim 9 and immunoglobulin, toxin or imageable compound. 11. An antibody that binds specifically to polypeptide according to claim 9. 12. The antibody according to claim 11 conjugated to a toxin or imageable compound. 13. A method of treating a subject with renal disorders selected from the group of acute renal failure, acute nephritis, chronic renal failure, nephrotic syndrome, renal tubule defects, kidney transplants, toxic injury, hypoxic injury, trauma, polycystic renal disease, juvenile nephrophthisis and medullary sponge kidney comprising administering to the subject a therapeutically effective amount of the nucleic acid according to claim 1 or 2 or the vector according to claim 5 or 6. 14. A method of promoting growth of new tissue in a subject, comprising administering to the subject a therapeutically effective amount of the nucleic acid according to claim 1 or 2 or the vector according to claim 5 or 6. 15. A method of promoting survival of damaged tissue in a subject, comprising administering to the subject a therapeutically effective amount of the nucleic acid according to claim 1 or 2 or the vector according to claim 5 or 6. 16. A method according to any one of claims 13-15 wherein the subject is a human. 17. A pharmaceutical composition comprising a physiologically acceptable carrier and further comprising a nucleic acid according to claim 1 or 2 or a vector according to claim 5 or 6 dispersed therein to a therapeutically effective concentration. 18. A method of assessing presence or course of resolution of rental injury in a subject, comprising the step of measuring the concentration of nucleic acid according to claim 1 or 2 in urine, serum or urine sediment of a subject afflicted with, or at a risk of developing, renal injury or disease. 19. A method of imaging cells or tissue producing a polypeptide according to claim 9, comprising the step of contacting the cells or tissue with antibody according to claim 12. 20. A method of treating a subject with renal disorders selected from the group of acute renal failure, acute nephritis, chronic renal failure, nephrotic syndrome, renal tubule defects, kidney transplants, toxic injury, hypoxic injury, trauma, polycystic renal disease, juvenile nephrophthisis and medullary sponge kidney comprising administering to the subject a therapeutically effective amount of the polypeptide according to claim 9. 21. A method of treating a subject with renal disorders selected from the group of acute renal failure, acute nephritis, chronic renal failure, nephrotic syndrome, renal tubule defects, kidney transplants, toxic injury, hypoxic injury, trauma, polycystic renal disease, juvenile nephrophthisis and medullary sponge kidney comprising administering to the subject a therapeutically effective amount of the antibody according to claim 11 or 12. 22. A method of promoting growth of new tissue in a subject, comprising administering to the subject a therapeutically effective amount of the polypeptide according to claim 9. 23. A method of promoting growth of new tissue in a subject, comprising administering to the subject a therapeutically effective amount of the antibody according to claim 11 or 12. 24. A method of promoting survival of damaged tissue in a subject, comprising administering to the subject a therapeutically effective amount of the polypeptide according to claim 9. 25. A method of promoting survival of damaged tissue in a subject, comprising administering to the subject a therapeutically effective amount of the antibody according to claim 11 or 12. 26. A pharmaceutical composition comprising a physiologically acceptable carrier and further comprising a polypeptide according to claim 9 dispersed therein to a therapeutically effective concentration. 27. A pharmaceutical composition comprising a physiologically acceptable carrier and further comprising an antibody according to claim 11 or 12 dispersed therein to a therapeutically effective concentration. 28. A method of assessing presence or course of resolution of rental injury in a subject, comprising the step of measuring the concentration of polypeptide according to claim 9 in urine, serum or urine sediment of a subject afflicted with, or at a risk of developing, renal injury or disease.