The bacterial response to DNA damage is known as the SOS response. There are two main proteins involved - one, LexA, to keep the response switched off while the cell is healthy and the other, RecA, to turn it on when DNA damage occurs. In normal healthy cells the LexA protein binds to a certain section of the bacterial DNA called the 'SOS box' which codes for over 50 genes while RecA floats around the cell looking for damaged DNA. If it finds any, it binds to it and stimulates the breaking of the LexA protein. The SOS box genes are therefore released and the proteins that deal with DNA damage can be made.