A freelance photographer Tuesday renewed his challenge to go three rounds in a boxing ring with actor Sean Penn, upping the ante to $6 million. "I'm serious about this, I'm just trying to stand up for the press," said Mick Paladin, a photographer who says he's tired of hearing about punches allegedly thrown at paparazzi who follow Penn. Paladin, 40, said Tuesday that a group of Phoenix, Ariz., businessmen offered to put up a $6-million purse. That raises the stakes considerably from last year, when Paladin put ads in entertainment trade magazines offering $50,000 in prize money if Penn would take him on. Paladin, in a telephone interview from Phoenix, said the purse would be split 50-50. Penn, 26, ignored his last challenge. His publicist failed to return calls Wednesday.