Variety reports that Oscar nominated actress Rooney Mara (Dragon Tattoo, Social Network) has signed on to replace Blake Likely in Steven Soderbergh's Side Effects. The financiers of the film backed out when the unproven Lively was cast in the lead role. Which forced Soderbergh to look at other actresses. Mara who isn't very well known has a bit of pedigree to her budding career starring in David Fincher's Social Network and Dragon Tattoo. The latter earned Rooney an Oscar nomination for best actress.