<i>B. subtilis</i> RecA protein accumulation upon SOS induction in different genetic backgrounds.

<p>Cells were grown to OD₅₆₀ = 0.4 in LB medium and exposed to increasing concentrations of MMC for 30 min. The cells were lysed and equivalent protein amounts subjected to 10% SDS-PAGE, followed by immunoblot transfer (see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003126#s4" target="_blank">Materials and Methods</a>). (A) <i>rec</i>⁺, Δ<i>recX</i>, Δ<i>lexA</i> and <i>recX</i>342 cells; (B) <i>rec</i>⁺, <i>recF</i>15, Δ<i>recX recF</i>15, Δ<i>recO</i> and Δ<i>recX</i> Δ<i>recO</i> cells. The results are the average of at least four independent experiments and the standard errors are indicated.