The link between mRNA sorting and protein location has been tested in transgenic mice models. The models were created so that the coding regions of Tropomyosin 5NM1/2 and Tropomyosin 3 were expressed under the control of the β-actin promoter with the a β-actin 3'-untranslated region lacking targeting information. The study found that Tropomyosin 3, an isoform that is not normally expressed in neuronal cells, was broadly distributed throughout the neuron, while exogenous expression of the neuronal isoform Tropomyosin 5NM1/2 was found to sort to the growth cone of neurons as does the endogenous Tropomyosin 5NM1/2. As these two transgenes differ only in the tropomyosin coding region yet are localized in two distinct areas, the findings suggest that, in addition to mRNA sorting, the proteins themselves contain sorting information.