On May 15th, California surgeon Rongxiang Xu announced that he is suing one of the Nobel Prize’s winners, Shinya Yamanaka, who was honored for his work on stem cells along with fellow scientist John Gurdon.

Xu, founder of the regenerative medicine company MEBO, claimed in his suit that Yamanaka is guilty of slander of title, defamation, trade libel, unfair competition, and negligent interference with prospective economic advantage. A press release said that Xu had patented the ability to turn differentiated somatic cells into stem cells before Yamanaka stated that he had done the same, detracting from Xu’s reputation.