Related Experiment Video
Updated: Apr 28, 2026

Differentiation of Mouse Breast Epithelial HC11 and EpH4 Cells
Published on: February 27, 2020
Cyclin D1 and C/EBPβ LAP1 operate in a common pathway to promote mammary epithelial cell differentiation
Qiang Liu1, Antoine Boudot2, Jing Ni3
1Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts, USA Dana-Farber Cancer Institute, Boston, Massachusetts, USA.
Abstract:
Both cyclin D1 and the transcription factor C/EBPβ are required for mammary epithelial cell differentiation; however, the pathway in which they operate is uncertain. Previous analyses of the patterns of gene expression in human tumors suggested a connection between cyclin D1 overexpression and C/EBPβ, but whether this represents a cancer-specific gain of function for cyclin D1 is unknown. C/EBPβ is an intronless gene encoding three protein isoforms--LAP1, LAP2, and LIP. Here, we provide evidence that cyclin D1 engages C/EBPβ in an isoform-specific manner. Cyclin D1 binds to LAP1, an event that activates the transcriptional function of LAP1 by relieving its autoinhibited state effected by intramolecular interactions. Reexpression of LAP1 but not LAP2 or LIP restores the ability of C/EBPβ-deficient mammary epithelial cells to differentiate and does so in a manner dependent on cyclin D1. And cyclin D1-mediated activation of LAP1 participates in mammary epithelial cell differentiation. Our findings indicate that cyclin D1 and C/EBPβ LAP1 operate in a common pathway to promote mammary epithelial cell differentiation.
Related Concept Videos
Positive Regulator Molecules
Positive Regulator Molecules
Mitogens and the Cell Cycle
Inhibition of Cdk Activity
Canonical Wnt Signaling Pathway
M-Cdk Drives Transition Into Mitosis
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...

