Does homologous recombination occur in mouse cells, specifically NIH-3T3 cells (fibroblasts)? I was wondering if you make a monoclonal heterozygote where a gene is KO in one chromosome but not the other, if this would be a stable system? I am specifically asking for CRISPR/Cas but if anyone has experience with monoclonal mouse heterozygote cell lines, I am sure the same principle applies. Thanks!