Mitogen

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MAP kinase activation
Mitogen
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MAP kinase kinase kinase (MAP3K or MKKK)
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MAP kinase kinase (MAP2K or MKK)
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MAP kinase
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further signalling

A mitogen is a chemical, usually some form of a protein that encourages a cell to commence cell division, triggering mitosis.

Mitogens trigger signal transduction pathways in which mitogen-activated protein kinase is involved, leading to mitosis.

[edit] Use in immunology

Plasma B cells can enter mitosis when they encounter an antigen matching their immunoglobulin.

Mitogens are often used to stimulate lymphoctyes and therefore assess immune function.

The most commonly used mitogens in clinical laboratory medicine are:

Name	Acts upon T cells?	Acts upon B cells?
phytohaemagglutinin (PHA)	yes	no
concanavalin A (conA)	yes	no
lipopolysaccharide (LPS)	no	yes
pokeweed mitogen (PWM)	yes	yes

LPS toxin from gram negative bacteria is thymus independent. They may directly activate B cells, regardless of their antigenic specificity

Plasma B cells are terminally differentiated and therefore cannot undergo mitosis. Memory B cells can proliferate to produce more memory cells or plasma B cells. This is how the mitogen works, by inducing mitosis in B cells to cause them to divide, with some becoming plasma.