Inherited diseases often result from a defective or missing gene. A goal of biochemistry is to eventually treat such diseases by replacing the defective gene with a functioning version. In the example of gene manipulation illustrated here, a recombinant gene consisting of the gene for the cytoskeleton protein actin linked to the gene for green fluorescent protein was inserted into a mouse embryo. The fluorescence photograph of the mouse shows the location of green fluorescent protein (GFP) attached to actin molecules. Hair has no actin and thus does not fluoresce.