To visualize the SOS response proteins inside bacteria, the E. coli were edited to create strains with fluorescently labeled recA and recN in their genome. The recA gene was fused with the mNeonGreen fluorescent protein, and the recN gene was fused with the mScarlet fluorescent protein. Fluorescence visualization of the resulting strain showed the synthesis of filaments and foci by the RecA protein during the bacterial SOS response, which in some cases colocalize with the RecN protein foci. Keywords: SOS response, RecA protein, RecN protein, CRISPR-Cas9, fluorescence microscopy.