Correction to: The Emerging Roles of Steroid Hormone Receptors in Ductal Carcinoma in Situ (DCIS) of the Breast.

The original version of this article unfortunately contained mistakes.

Epithelial and non-epithelial play opposing roles to regulate proliferation and morphogenesis of the mouse mammary gland.

Patched 1 () has epithelial, stromal and systemic roles in murine mammary gland organogenesis, yet specific functions remain undefined. -recombinase-mediated ablation in mammary epithelium increased proliferation and branching, but did not phenocopy transgenic expression of activated smoothened (). The epithelium showed no evidence of canonical hedgehog signaling, and hyperproliferation was not blocked by smoothened (SMO) inhibition, suggesting a non-canonical function of PTCH1.

An essential role for Gα(i2) in Smoothened-stimulated epithelial cell proliferation in the mammary gland.

Hedgehog (Hh) signaling is critical for organogenesis, tissue homeostasis, and stem cell maintenance. The gene encoding Smoothened (SMO), the primary effector of Hh signaling, is expressed aberrantly in human breast cancer, as well as in other cancers. In mice that express a constitutively active form of SMO that does not require Hh stimulation in mammary glands, the cells near the transgenic cells proliferate and participate in hyperplasia formation.

Altered differentiation and paracrine stimulation of mammary epithelial cell proliferation by conditionally activated Smoothened.

The Hedgehog (Hh) signaling network is critical for patterning and organogenesis in mammals, and has been implicated in a variety of cancers. Smoothened (Smo), the gene encoding the principal signal transducer, is overexpressed frequently in breast cancer, and constitutive activation in MMTV-SmoM2 transgenic mice caused alterations in mammary gland morphology, increased proliferation, and changes in stem/progenitor cell number. Both in transgenic mice and in clinical specimens, proliferative cells did not usually express detectable Smo, suggesting the hypothesis that Smo functioned in a non-cell autonomous manner to stimulate proliferation.

Hedgehog signaling in the normal and neoplastic mammary gland.

The hedgehog signal transduction network is a critical regulator of metazoan development. Inappropriate activation of this network is implicated in several different cancers, including breast. Genetic evidence in mice as well as molecular biological studies in human cells clearly indicate that activated signaling can lead to mammary hyperplasia and, in some cases, tumor formation.

CCAAT/enhancer binding protein beta regulates stem cell activity and specifies luminal cell fate in the mammary gland.

The bZIP transcription factor C/EBP beta is important for mammary gland development and its expression is deregulated in human breast cancer. To determine whether C/EBP beta regulates mammary stem cells (MaSCs), we employed two different knockout strategies. Using both a germline and a conditional knockout strategy, we demonstrate that mammosphere formation was significantly decreased in C/EBP beta-deficient mammary epithelial cells (MECs).

Methods for preparing fluorescent and neutral red-stained whole mounts of mouse mammary glands.

Whole mount preparations of mouse mammary glands are useful for evaluating overall changes in growth and morphology, and are essential for detecting and evaluating focal or regionally-localized phenotypes that would be difficult to detect or analyze using other techniques. We present three newly developed methods for preparing whole mounts of mammary glands from genetically-engineered mice expressing fluorescent proteins, as well as using either neutral red or a variety of fluorescent dyes. Unlike traditional hematoxylin- or carmine-stained preparations, neutral red-stained and some fluorescent preparations can be used for several common downstream analyses.