This kit, based on cells, enables screening or identifying agents (drugs, natural products, small molecules, synthetics, miRNAs, and genes) that influence or affect HR DNA repair. It employs GFP as an in vivo readout for the HR pathway and a CRISPR-CAS gRNA plasmid causing a DS DNA break in Cassette 1. This break induces HR in a mutated GFP reporter gene, which recombines with Cassette 2 containing WT GFP, resulting in GFP+ cells upon HR completion.