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Reviewed August 2013

What is the official name of the CDKN1B gene?

The official name of this gene is “cyclin-dependent kinase inhibitor 1B (p27, Kip1).”

CDKN1B is the gene's official symbol. The CDKN1B gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the CDKN1B gene?

The CDKN1B gene provides instructions for making a protein called p27. This protein is found in cells and tissues throughout the body. Within cells, p27 is located primarily in the nucleus, where it plays a critical role in controlling cell growth and division. It helps regulate the cell cycle, which is the cell's way of replicating itself in an organized, step-by-step fashion. Specifically, p27 normally blocks cells from entering the phase of the cell cycle when DNA is copied (replicated) in preparation for cell division. By blocking cell cycle progression, p27 prevents cells from dividing too quickly or at the wrong time. Based on this function, p27 is described as a tumor suppressor protein. Studies suggest that p27 is also involved in controlling cell differentiation, which is the process by which cells mature to carry out specific functions.

Because p27 plays such a key role in controlling cell division, its activity is tightly regulated. Regulation can occur through modification of the p27 protein's structure, its interaction with other proteins, or its localization within the cell. For example, when p27 is held (sequestered) in the fluid that surrounds the nucleus (the cytoplasm) instead of being transported into the nucleus, the protein is unavailable to block cell cycle progression. Researchers believe that p27 may have other functions in the cytoplasm, but these functions have not been well described.

How are changes in the CDKN1B gene related to health conditions?

multiple endocrine neoplasia - caused by mutations in the CDKN1B gene

At least eight mutations in the CDKN1B gene have been found to cause a relatively rare form of multiple endocrine neoplasia called type 4. Multiple endocrine neoplasia typically involves the development of tumors in two or more of the body's hormone-producing glands, called endocrine glands. These tumors can be noncancerous or cancerous. The most common endocrine glands affected in multiple endocrine neoplasia type 4 are the parathyroid glands and the pituitary gland, although additional endocrine glands and other organs can also be involved.

Most of the CDKN1B gene mutations that cause multiple endocrine neoplasia type 4 change single protein building blocks (amino acids) in the p27 protein. Some mutations impair the protein's ability to interact with regulatory proteins, while others lead to the production of an unstable version of p27 that is quickly broken down. Still other mutations prevent p27 from moving from the cytoplasm into the nucleus. All of these mutations reduce the amount of functional p27 that is available in the nucleus to regulate the cell cycle. Cells with a shortage of functional p27 can divide too quickly or in an uncontrolled way, forming a tumor. It is unclear why these tumors occur primarily in endocrine glands; studies suggest that certain endocrine cells may be particularly dependent on the p27 protein to control cell division.

other tumors - associated with the CDKN1B gene

Mutations in the CDKN1B gene have also been found to cause tumors in single endocrine glands, such as the pituitary gland or the parathyroid glands. These mutations are described as somatic; they are not inherited and are present only in tumor cells. Somatic CDKN1B gene mutations have been identified in sporadic (nonfamilial) pituitary adenomas and in sporadic parathyroid adenomas, which are noncancerous tumors of the parathyroid glands. Like the mutations that cause multiple endocrine neoplasia type 4, these genetic changes reduce the amount of functional p27 available to control cell division. As a result, cells become more likely to divide abnormally and form a tumor.

Apart from multiple endocrine neoplasia, the CDKN1B gene is rarely mutated in cancerous tumors. However, changes in regulation that reduce the amount or function of the p27 protein in the nucleus are found in many types of cancer. A shortage of p27 has been associated with more aggressive tumors and a poorer prognosis.

Where is the CDKN1B gene located?

Cytogenetic Location: 12p13.1-p12

Molecular Location on chromosome 12: base pairs 12,717,270 to 12,722,383

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)

The CDKN1B gene is located on the short (p) arm of chromosome 12 between positions 13.1 and 12.

The CDKN1B gene is located on the short (p) arm of chromosome 12 between positions 13.1 and 12.

More precisely, the CDKN1B gene is located from base pair 12,717,270 to base pair 12,722,383 on chromosome 12.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about CDKN1B?

You and your healthcare professional may find the following resources about CDKN1B helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the CDKN1B gene or gene products?

  • CDKN4
  • cyclin-dependent kinase inhibitor 1B
  • KIP1
  • MEN1B
  • MEN4
  • P27KIP1

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding CDKN1B?

acids ; cancer ; cell ; cell cycle ; cell division ; cytoplasm ; differentiation ; DNA ; gene ; hormone ; inherited ; kinase ; neoplasia ; nucleus ; parathyroid ; pituitary gland ; prognosis ; progression ; protein ; sporadic ; tumor

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (8 links)


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

Reviewed: August 2013
Published: February 8, 2016