Fade a class in?

Question

I've got a <td>. It has a class applied which specifies a background color. Can I fade-in to a different class, which just has a different background color? Something like:

// css
.class1 {
  background-color: red;
}

.class2 {
  background-color: green;
}

$('#mytd').addClass('green'); // <- animate this?

Thanks