Jay-Z is stepping down as CEO and president of Island Def Jam records.The hip-hop mogul was reportedly unimpressed with the appointment of producer Jermaine Dupri as president of the label's urban music division in February this year and is now in talks to quit the company. A source told the New York Daily News newspaper: "There isn't room for two kings at one label."Why would Def Jam bring in another power-hitter urban guy?"Jay-Z is now reportedly considering moving to Columbia records, the home of his girlfriend Beyoncé Knowles.The 38-year-old rapper is expected to take ownership of the master recordings of his musical catalogue with him when he moves.Jay-Z has been responsible for signing a number of major music stars to the label, including his 19-year-old protégée Rhianna - who he signed to Def Jam in 2004.The hip-hop mogul's success with the young songstress has made him an attractive option for Columbia co-chair Rick Rubin.A source said: "Rick's creating a super group of staff. So it would make sense that he would want Jay on his side."