Sure you can but you will earn nothing or very litte.
It's Kh/s
There is bunch of new alt coins to mine with GPU.
This is sad to know. I hoped that this algorithm would still give gpu miners a chance. I saw several Litecoin mining rigs on the internet, and most of them used gpus. They're probably pictures of when it was still worth mining with it.
Luckily there are many altcoins that can still be profitable, but this will probably be worth it only for people with low electricity costs.