Fifty Shades of Grey star Dakota Johnson has signed on to star in the upcoming New Line romantic comedy How to Be Single, along with other new casting additions Rebel Wilson, Dan Stevens and Leslie Mann. Community star Alison Brie is also in final negotiations to join the cast. We first reported on the project back in February, when Lily Collins was in talks to come on board, but it isn't known if she is still involved, since she wasn't mentioned in The Hollywood Reporter's new report.The story is adapted from Liz Tuccillo's 2008 novel of the same name, which will be an ensemble comedy featuring intersecting stories, in the same vein as Valentine's Day and He's Just Not That Into You.