- Loss of imprinting of insulin-like growth factor-II in Wilms' tumor commonly involves altered methylation but not mutations of CTCF or its binding site. Cui, H., Niemitz, E.L., Ravenel, J.D., Onyango, P., Brandenburg, S.A., Lobanenkov, V.V., Feinberg, A.P. Cancer Res. (2001)