I saw on cfl.ca that the Riders released non-import defensive end Shomari Williams. Williams was drafted first overall by the Riders in 2010. Williams signed in 2013 with the Cats as a free agent and was pretty much injured the entire season, which was a major disappointment. The Cats traded him back to the Riders for the 2014 season.
Williams as a non-import was likely drawing a large salary, but only appeared to play special teams in 2014 with 17 special teams tackles. I'm doubting the Cats would sign him as they have plenty of Canadian (arguably too much) defensive line talent.