- Inhibitor of growth 4 (ING4) is up-regulated by a low K intake and suppresses renal outer medullary K channels (ROMK) by MAPK stimulation. Zhang, X., Lin, D.H., Jin, Y., Wang, K.S., Zhang, Y., Babilonia, E., Wang, Z., Wang, Z., Giebisch, G., Han, Z.G., Wang, W.H. Proc. Natl. Acad. Sci. U.S.A. (2007)