To determine the role of this ccRCC tumor cell-specific V2R in the regulation of fibroblasts, undifferentiated rat renal fibroblasts (NRK-49F cells) were exposed to serum-free cell culture conditioned media (CM) from Caki1 cells, a human ccRCC tumor cell line. The gene discussed is AVPR2; the disease is nonpapillary renal cell carcinoma.