Marks made the right connection with Guo. She worked with lab post-doc Dr. Wei Wang on studying biomarkers for breast cancer. Two years later, that research is about to be published in the journal Oncogene and brought a first-place prize for Guo and her N.C. School of Science and Math classmate Xianlin Li in the Siemens-Westinghouse Competition in Science, Mathematics and Technology.

In the aftermath of her triumph in the Siemens-Westinghouse competition (which included a $100,000 prize), Guo said her work with Wang in Marks' lab was "a priceless experience."

"I especially enjoyed going to the lab meetings, where the scientists shared the data they collected. Through the process of mundane collecting data, I realized that the process of science was not as glamorous as others said it would be. However, the feeling of venturing into the unknown was very gratifying. My interest in biology increased tremendously through working on the project."

In the lab, Guo studied the genetics and molecular biology of breast cancer. Duke researchers have identified a genetic variation called BRCA1 that is responsible for 5 percent of all breast cancer cases, but researchers believe the gene may play some role in the other 95 percent of cases as well.

Specifically, Guo studied the role of DNA methylation, a natural gene-silencing process, on breast cancer. The research showed that cancer cells are able to hinder a particular tumor-suppressor gene through methylation. Marks said the research has two possible implications: it might provide physicians with a biomarker to make an early diagnosis of breast cancer and it adds to the general information about how the BRCA 1 pathway works.

"Her project is part of a larger project in this area of study," Marks said. "We often discussed what her work meant within this larger framework. It's complicated science, but she understood the research."

Six months after Guo completed her work, she and Li met with Marks to prepare for the regionals of the Siemens-Westinghouse competition. Li, who didn't work in Marks lab but did research at Duke through the Howard Hughes Pre-College program, helped Guo work on the project and its presentation. The three met once more before the finals to discuss the presentation. One thing that impressed him was how the two were able to express a passion for science.

"They're brilliant kids. I think what really made the difference for them in the competition was that they conveyed the science underneath the work perfectly," Marks said. "They addressed all the main issues and really showed they understood it."

Guo said the sessions with Marks prepared them well for the tough questioning they received from the competition's judges. Afterwards, she had only praise for Marks and Wang and the many teachers at the School of Science and Math who assisted the two students.

"At nationals, we were surprised to find that the questions that the judges asked were less focused on the background knowledge and more focused on the future applications of the work," she said. "Therefore, they tested not only our knowledge of the field but also our creativity in taking the research a step further.

"We knew that the competition was going to be more intense at nationals. Throughout the entire process of the competition, we never really had a feeling that it was going 'well,'" she added.

"The projects at both regionals and nationals completely blew us away, and we were extremely impressed with the work conducted by other students across the country. Getting to see everyone else's presentations and learning about their work was incredibly rewarding, and speaking to the judges who were interested in our project was an invigorating experience."