Ocampo and Juan Carlos Izpisua Belmonte, a developmental biologist at Salk, realized that reducing the amount of mutant mitochondrial DNA in an egg or fertilized embryo could reduce the chance of disease developing. They did this by injecting the cells with a segment of RNA that was designed to produce a DNA-cutting enzyme known as an endonuclease. The endonuclease would then seek out mitochondria with a specific mutation and destroy their DNA by snipping it.