as part of Worldwide Studios. On August 23, 2010, the headquarters of the company moved from Minami-Aoyama to the (Sony Corporation's headquarters) in Kōnan, Minato, Tokyo. On April 20, 2011, SCEI was the victim of an attack on its PlayStation Network system, which also affected its online division, Sony Online Entertainment. On August 1, 2011, video game developer Sucker Punch Productions, developers of the Sly Cooper and Infamous series, was also acquired. Launch of PlayStation Vita and PlayStation 4, expansion into China (2011–2016) In January 2012, BigBig Studios was closed and Cambridge Studio—renamed Guerrilla Cambridge—becoming a sister studio of Guerrilla Games. In March 2012, Zipper Interactive, developers of the SOCOM series, MAG and Unit 13, was closed. On June 25, 2012, Hirai retired as chairman of Sony Computer Entertainment; however, he remains on the board of directors. On July 2, 2012, Sony Computer Entertainment acquired Gaikai, a cloud-based gaming service. In August 2012, Studio Liverpool, developer of the Wipeout and Formula One series, was closed. In August 2012, Sony Computer Entertainment announced PlayStation Mobile for Vita and PlayStation certified devices, with a developers such has THQ, Team17 and Action Button Entertainment signed up. A press release was published on August 20, 2013, announcing the release date of the PlayStation 4 (PS4) console. On that date, SCEI introduced the CUH-1000A series system, and announced the launch date as November 15, 2013, for North American markets and November 29, 2013, for European, Australasian and Central and South American markets. Following a January 2014 announcement by the Chinese government that the country's 14-year game console ban would be lifted, the PS4 was scheduled to be the first Sony video game console to be officially and legally released in China since the PlayStation 2. On March 6, 2014, Sony Computer Entertainment of America President and CEO, Tretton, announced he was resigning from his position at the end of the month, citing a mutual agreement between himself and SCEA for the cessation of his contract. Tretton had worked at SCEA since 1995 and was a founding member of the company's executive team. He was involved in the launch of all PlayStation platforms in North America, including the original PlayStation, PS2, PSP, PS3, PSN, PS Vita, and PS4. Tretton was replaced by Shawn Layden, who was the vice-president and chief operating officer (COO) of Sony Network Entertainment International, effective April 1, 2014. On April 2, 2015,