The Nevada Athletic Commission (NAC) conducted in competition and out-of-competition drug tests on fighters from UFC 189. All of them have come back negative, the NAC announced Monday.

Conor McGregor, Chad Mendes, Rory MacDonald, Robbie Lawler, Dennis Bermudez and Jeremy Stephens were all subjected to out-of-competition testing -- blood and urine -- and all of them were clean, according to the results posted on the NAC website. The fight-night tests taken July 11 for those six men were also negative. The tests were sent to Sports Medicine Research & Testing in Salt Lake City.

Every other fighter was also tested on fight night and those screens also came back negative, per the website. Those screens, all urine, were sent to Quest Diagnostics in Las Vegas.

McGregor was tested out of competition May 23 and Mendes was tested July 5, six days before the fight since he was a late replacement for Jose Aldo on the Las Vegas card. As previously reported, Aldo's controversial out-of-competition test came back negative as well.

Lawler and MacDonald were each tested out of competition twice. Lawler was tested June 5 and June 17, while MacDonald was tested June 6 and June 16.

Stephens was tested June 1, and Bermudez was tested June 7.

As per policy, the NAC does not release out-of-competition screening results, even though it gets them back before fight night, until after the event. If a fighter tests positive, the NAC informs the fighter and promotion, deferring to the promotion to announce the result. If the promotion does not announce the negative result, then the NAC will.