- Down-regulation of Smad7 expression by ubiquitin-dependent degradation contributes to renal fibrosis in obstructive nephropathy in mice. Fukasawa, H., Yamamoto, T., Togawa, A., Ohashi, N., Fujigaki, Y., Oda, T., Uchida, C., Kitagawa, K., Hattori, T., Suzuki, S., Kitagawa, M., Hishida, A. Proc. Natl. Acad. Sci. U.S.A. (2004)