How can I remove paint stains from my T-shirt?

The theme at a party I went to a while ago was “Glow in the Dark”, and since I had just bought a new T-shirt with glow-in-the-dark print I wore it there.

Unfortunately, someone else thought it’d be cool to bring glow-in-the-dark paint, which got on my brand new T-shirt.

I bought stain remover and have washed it several times using it, but there still is a smear of white glow-in-the-dark paint on the back. Does anyone have any great tips on how to remove them properly?