NK2 homeobox 1 (NKX2-1), also known as thyroid transcription factor 1 (TTF-1), is a protein which in humans is encoded by the NKX2-1 gene.

Thyroid transcription factor-1 (TTF-1) is a protein that regulates transcription of genes specific for the thyroid, lung, and diencephalon. It is also known as thyroid specific enhancer binding protein. It is used in anatomic pathology as a marker to determine if a tumor arises from the lung or thyroid.

TTF-1 positive cells are found in the lung as type II pneumocytes and Clara cells. In the thyroid, follicular and parafollicular cells are also positive for TTF-1.

For lung cancers, adenocarcinomas are usually positive, while squamous cell carcinomas and large cell carcinomas are rarely positive. Small cell carcinomas (of any primary site) are usually positive. TTF1 is more than merely a clinical marker of lung adenocarcinoma. It plays an active role in sustaining lung cancer cells in view of the experimental observation that it is mutated in lung cancer.

Eric Steven Lander (born February 3, 1957) is a Professor of Biology at the Massachusetts Institute of Technology (MIT), a member of the Whitehead Institute, and director of the Broad Institute of MIT and Harvard who has devoted his career toward realizing the promise of the human genome for medicine. He is co-chair of U.S. President Barack Obama's Council of Advisors on Science and Technology.

He was captain of the math team at Stuyvesant High School and an International Mathematical Olympiad Silver Medalist for the United States, graduating from high school in 1974. At the age of seventeen, he wrote a paper on quasiperfect numbers for which he won the Westinghouse Prize. He attended Princeton University, where he graduated in 1978 as valedictorian. He wrote his doctorate on symmetric designs at Oxford University as a Rhodes Scholar, under the supervision of Peter Cameron. As a mathematician he studied combinatorics and applications of representation theory to coding theory. He enjoyed mathematics but did not wish to spend his life in such a "monastic career." Unsure of what to do next, he took up a job teaching managerial economics at Harvard Business School; he also began to write a book on information theory. At the suggestion of his brother, Arthur Lander, he started to look at neurobiology "because there's a lot of information in the brain." In order to understand mathematical neurobiology, he felt he had to study cellular neurobiology; this in turn led to studying microbiology and continued down to the level of genetics. "When I finally feel I have learned genetics, I should get back to these other problems. But I'm still trying to get the genetics right".