sentence: Pigs bridge the gap between humans and the heavily used small rodent models to favor biomedical research ranging from basic science to translational medicine.However , production of gene-targeted mammals other than mice remained difficult until the late 2000s because the traditional gene targeting technique developed in mice requires homologous recombination ( HR ) manipulation in embryonic stem ( ES ) cells ( Mansour et al ., 1988 ; Capecchi , 1989 ) .