 A Japanese company has defended its ownership of Van Goghs Sunflowers, obtained at auction in 1987, after the family of its former owner filed a US lawsuit demanding its return.The artwork -- one of five original versions of the famous still life -- was purchased by the predecessor of insurance firm Sompo Holdings at Christies in London for 40 million, making it briefly the worlds most expensive painting.It has been on display in Tokyo at Sompos art museum for 35 years, but recently becam... 