Cleavage of both LexA and UmuD is stimulated by a protein called RecA, which is activated by single-stranded DNA resulting from DNA damage.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

One individual, however, expresses only a small number of these molecules—up to six different class I molecules and 12 or more different class II molecules.

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#Id: 1745

#Unit 4. Cell Communication and Cell Signaling

MHC molecules in mouse

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#Id: 1746

#Unit 4. Cell Communication and Cell Signaling

IFN-  has been shown to induce expression of the class II transcriptional activator (CIITA).

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#Unit 4. Cell Communication and Cell Signaling

IL-4 increases expression of class II molecules in resting B cells, turning them into more efficient APCs.

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#Unit 4. Cell Communication and Cell Signaling

Expression of class II molecules by B cells is down-regulated by IFN- .

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Corticosteroids and prostaglandins can also decrease expression of class II MHC molecules.