Figure 7.

Revised model of the major CHO cell DSB repair pathways. A novel model describing the possible interplay of the NHEJ, HR, MMEJ, and two distinct SD‐MMEJ pathways involved in DSB repair in CHO cells, as modified from Supplementary Figure S3. Although the junction sequences resulting from both SD‐MMEJ pathways are similar, the Ligase I‐dependent SD‐MMEJ requires the homology‐searching Rad51 protein, and it may provide a fallback mechanism in the absence of extensive homology, as required to complete HR. Activities that initiate MMEJ and Ligase III‐dependent SD‐MMEJ remain to be identified, but the presence or absence of pre‐existing microhomologies may dictate the choice between these two pathways.