Model for the regulation of nascent D-loop stability in S. cerevisiae. The mechanism by which Rdh54 demarcates these two pathways and/or D-loop types is not known. The human homologs of STR (Sgs1-Top3-Rmi1) is BLM-TOPOIIIα-RMI1/2, of Mph1 is FANCM, and of Rdh54 is possibly RAD54B. Putative functional homologs of Srs2 in human include BLM, FANCJ, FBH1, PARI, RECQ1, RECQ5 and RTEL1. The thickness of the arrows reflects pathway usage