RS-1 is a RAD51 activator. RS-1 also increases CRISPR/Cas9-mediated knock-in efficiencies.

RS-1 serves as an activator of RAD51, enhancing the binding affinity of hRAD51 to DNA, with a dissociation constant (Kd) between 48 nM and 107 nM, in conditions containing ATP or ADP and even in the absence of nucleotide cofactors, without inhibiting ATPase activity of RAD51. At a concentration of 20 μM, RS-1 alters the length and helical pitch of hRAD51-DNA complexes. Furthermore, RS-1 progressively augments the strand assimilation activity of hRAD51 across a range of concentrations (0, 1, 5, 10, 15, 20, and 25 μM). At 7.5 μM, it bolsters human cells' resilience to cross-linking agents used in chemotherapy[1]. In addition, RS-1 enhances Cas9-mediated gene editing efficiency in rabbit embryos at concentrations of 0, 7.5, and 15 μM[2].