Fig. 8: A model for MCM8/9 aiding in normal fork progression or directing reversed fork protection during persistent obstacles.

a MCM8 and 9 participate within the replisome to overcome transient blocks (yellow hexagon) to fork progression and limit fork processing to maintain genomic integrity. b Should the replisome encounter persistent blocks (red hexagon), MCM8/9 works to recruit RAD51 and BRCA1 to stabilized and protect SMARCAL1 reversed and stalled forks from MRE11 (shaded) degradation. c In the absence of MCM8/9, any endogenous stressors allow for unregulated fork reversal and degradation through a SMARCAL1/MRE11/MUS81 pathway, resulting in increased fork cleavage and DSBs.