An Andy Warhol portrait of Mao Zedong from 1972---which "Easy Rider" star and director Dennis Hopper shot two bullet holes through---went for $302,500, more than ten times the high estimate, at a Christie's auction this week.

Warhol later called Hopper a collaborator on the piece.

The late Hopper began collecting art in the 1960s after actor Vincent Price, an avid collector of impressionist art, told him: "You need to collect. This is where you need to put your money," said Cathy Elkies, director of iconic collections for Christie's, in the Washington Post.

More than 300 lots of fine art and memorabilia collected by the movie star, who died at 74 in May 2010, were auctioned by Christie's this week. A previous sale of items from his estate netted $12 million.