RS-1 is a stimulator of the human homologous recombination protein RAD51,enhances homology-directed repair ~2 to 5-fold and increases CRISPR-mediated knock-in efficiencies in vitro and in vivo.

SCR7 pyrazine is a DNA ligase IV inhibitor that blocks nonhomologous end-joining (NHEJ) in a ligase IV-dependent manner. SCR7 pyrazine is also a CRISPR/Cas9 enhancer which increases the efficiency of Cas9-mediated homology-directed repair (HDR). SCR7 pyrazine induces cell apoptosis and has anticancer activity.