Glossary

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Apoptosis: A type of cell death in which a series of molecular steps in a cell leads to its death. This is the body's normal way of getting rid of unneeded or abnormal cells. The process of apoptosis may be blocked in cancer cells. Also called programmed cell death.

BRAF: BRAF is a member of the RAF family of serine/threonine kinases and is an integral part of the RAS-RAF pathway.

ERK: Extracellular signal-regulated kinase (ERK) is a protein kinase that is a part of the RAS-RAF pathway. ERK is a type of MAPK. Activation of ERK results in the activation of transcription factors that lead to the expression of genes. These genes regulate cell proliferation and survival.

MAPK: Mitogen activated protein kinases (MAPKs) are enzymes with serine/threonine kinase activity (eg, ERK). MAPKs regulate various cellular processes, such as cell proliferation and cell differentiation, via downstream cellular regulatory targets in response to extracellular stimuli.
MEK: MEK is a protein kinase that is a part of the RAS-RAF signaling cascade that regulates expression of a large number of proteins involved in the control of cell proliferation, differentiation, and apoptosis.
Melanocyte: A type of cell found in the epidermis; it contains melanosomes that produce melanin.

Nevi: Plural of nevus. Any congenital lesion of the skin.
NRAS: NRAS is a member of the RAS family of human proto-oncogenes. Members of this family of proteins regulate and mediate cellular responses to growth signals, and specific point mutations in NRAS can lead to oncogenesis.

RAS-RAF pathway: The RAS-RAF signaling cascade couples signals from cell surface receptors to transcription factors, which in turn regulate cell growth, cell proliferation, and cell differentiation.
RAF: RAF is a protein kinase family implicated in cellular responses relevant to tumorigenesis, including cell proliferation, invasion, survival, and angiogenesis. The RAF family is composed of 3 members, ARAF, BRAF, and CRAF, each of which has a different function and is differentially regulated at various levels.
RAS: RAS is a GTP-binding protein that is activated in response to the binding of growth factors, cytokines, and hormones to cell surface receptors. The GTP-bound forms of RAS directly bind and recruit RAF to the plasma membrane.
Receptor tyrosine kinases (RTKs): Receptor tyrosine kinases are membrane-spanning, cell-surface proteins that contain an N-terminal extracellular ligand binding domain and a C-terminal intracellular tyrosine kinase domain.