No, it will not cause the entire project to be GPL.<p>The part that is GPL will have to be GPL, and everything else need to be compatible with GPL in order to satisfy the conditions of the license. MIT is compatible, so there is no problem. Going forward, no changes need to be done to the projects license, people can still submit patches under MIT, and so on.<p>There is a minor consideration. If someone forks your MIT project and puts it into a proprietary product, then the GPL file need to be removed.