Strategy for mutant telomere synthesis in human cancer cells. Strategy for mutant telomere synthesis in human cancer cells. An example of mutated bases in the telomerase RNA and complementary mutant DNA bases incorporated into telomeric DNA (red A's and T's, respectively) through copying of the mutant telomerase template. Lower left, schematic of the uncapping of telomeres. Ovals and diamonds, sequence-specific DNA binding proteins that protect telomeric DNA and cap it; red, telomerase; blue Xs, mutated telomerase RNA template and correspondingly mutated telomeric DNA sequence. Reproduced from the Proceedings of the National Academy of Sciences, U.S.A., 2001;98:7982–7 by copyright permission of the National Academy of Sciences, U.S.A. (5). Elizabeth H. Blackburn Mol Cancer Res 2005;3:477-482 ©2005 by American Association for Cancer Research