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General Transcription Factors

General Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...

Transcription Factors

Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...

Transcription Factors

Transcription Factors

Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...

Master Transcription Regulators

Master Transcription Regulators

Master transcription regulators are regulatory proteins that are predominantly responsible for regulating the expression of multiple genes. Often these genes work in concert to drive a complex process. Activation of a master transcription regulator can lead to a cascade of transcriptional activation necessary for that outcome. These regulators can directly bind to the regulatory sequences of the various genes involved, or they can indirectly regulate transcription by binding to regulatory...

Synthesis and Regulation of Thyroid Hormones

Synthesis and Regulation of Thyroid Hormones

Low blood levels of the thyroid hormones — triiodothyronine (T3) and thyroxine (T4) — signal the hypothalamus to release the thyrotropin-releasing hormone (TRH). TRH then reaches the pituitary gland and stimulates the release of thyroid-stimulating hormone(TSH) into the bloodstream.
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...

TGF - β Signaling Pathway

TGF - β Signaling Pathway

The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...

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Related Experiment Video

Updated: Jun 6, 2026

Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material

Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material

Published on: August 1, 2018

Thyroid transcription factor-1 expression in breast carcinomas.

Judith Robens¹, Lynn Goldstein, Allen M Gown

¹Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.

The American Journal of Surgical Pathology

|November 26, 2010

Summary

Thyroid transcription factor-1 (TTF-1) is typically found in thyroid and lung cancers. This study found TTF-1 expression in 2.4% of breast carcinomas, challenging its use to exclude breast cancer origin.

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Orthotopic Transplantation of Breast Tumors as Preclinical Models for Breast Cancer

Orthotopic Transplantation of Breast Tumors as Preclinical Models for Breast Cancer

Published on: May 18, 2020

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Last Updated: Jun 6, 2026

Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material

Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material

Published on: August 1, 2018

Orthotopic Transplantation of Breast Tumors as Preclinical Models for Breast Cancer

Orthotopic Transplantation of Breast Tumors as Preclinical Models for Breast Cancer

Published on: May 18, 2020

Area of Science:

Oncology
Pathology
Immunohistochemistry

Background:

Thyroid transcription factor-1 (TTF-1) immunostaining aids in determining metastatic carcinoma origin.
TTF-1 is predominantly expressed in thyroid and lung cancers.
Expression of TTF-1 has historically excluded breast carcinoma as a primary site.

Purpose of the Study:

To investigate the frequency of TTF-1 expression in primary breast carcinomas.
To determine if TTF-1 positivity can exclude a breast origin for carcinomas.

Main Methods:

Immunohistochemical staining for TTF-1 was performed on 546 primary breast carcinomas.
Cases were assessed for any nuclear staining for TTF-1.
Breast carcinomas were also tested for estrogen receptor, progesterone receptor, and HER2 status.

Main Results:

TTF-1 expression was identified in 13 out of 546 primary breast carcinomas (2.4%).
The observed TTF-1 expression ranged from focal and weak to diffuse and strong.
TTF-1 positivity was noted in both invasive and in situ components of the breast carcinomas.

Conclusions:

A small subset of breast carcinomas exhibit TTF-1 expression.
The presence of TTF-1 immunoreactivity alone is insufficient to rule out a breast origin for a carcinoma.