AUSTIN, Texas - Lance Armstrong shook off the cloud of doping allegations dogging him Friday as he urged backers of his Livestrong charity to continue the fight against cancer.
Armstrong founded Livestrong after his own battle with testicular cancer, but this week stepped down as its chairman after the US Anti-Doping Agency released a devastating report that placed the Texan at the heart of what it said was the biggest doping program in sports history.
Corporate sponsors including sportswear giant Nike have cut ties with Armstrong, but have said they will continue to support Livestrong.
"The mission absolutely must go on," Armstrong said.
Even so, it remains to be seen if the foundation will weather the scandal, with some saying Armstrong -- who remains on the board -- should break with the organization completely.
Access was tightly controlled for the event, where Armstrong received a warm welcome from some 1,500 supporters and cancer survivors.
Livestrong offered a glimpse of the man himself via YouTube, and his hometown paper, the Austin American-Statesman, reported Armstrong made just a glancing reference to the doping controversy when he said: "It's been a difficult couple of weeks for me and my family, my friends and this foundation."
Sean Penn, among the actors lending a bit of Hollywood glamor to the occasion, said he came to support both Armstrong and the foundation.
"I'm here for both," the Oscar-winning actor said as he headed into the Austin Convention Center via the "Yellow Carpet" -- a nod to the yellow rubber Livestrong bracelets worn to promote cancer awareness.
"Lance has developed an organization that has become an inspiration to me and to others -- and I think it will remain."
Asked if Armstrong is still an inspiration, Penn said: "I think to anyone who looks at this with a clear eye will see it as hypocritical to think otherwise."
It's a different take on Armstrong now that USADA's bombshell report has made him an outcast in cycling.
In support of the life ban it meted out to Armstrong in August, USADA published a damning dossier in which more than two dozen witnesses described his role in a doping scheme that helped him win seven Tour de France titles.
The International Cycling Union (UCI) said on Friday that it would respond to USADA's report on Monday in Geneva.
The body has to decide whether to endorse or reject USADA's ban and the removal of his Tour titles.
One longtime cycling sponsor decided not to wait for the UCI.
Rabobank, which has sponsored a professional cycling team for the last 17 years, claimed the sport had been irrevocably damaged by a succession of doping cases, and the report on Armstrong was the last straw.
"We are no longer convinced that the international professional world of cycling can make this a clean and fair sport," Rabobank board member Bert Bruggink said in a statement. "We are not confident that this will change for the better in the foreseeable future," he said.
"What the USADA showed us is that international cycle racing is not only sick but also at the highest level within cycling, including a number of the relevant authorities, including checks on the use of doping," he added.
Rabobank has been the standard-bearer for Dutch cycling and enjoyed success but it has also been mired in doping scandals, including one involving Danish rider Michael Rasmussen when he was wearing the leader's yellow jersey on the 2007 Tour de France.
On Thursday, the team said it had suspended Spanish cyclist Carlos Barredo after it was announced that he was facing disciplinary action from the UCI for allegedly breaking blood-doping rules.
Meanwhile, a report in Italy's Gazzetta dello Sport newspaper on Thursday claimed that a host of top riders and even whole teams were linked to the sports doctor who oversaw Armstrong's doping programme, stoking fears of fresh controversy.
Livestrong expected to raise $2.5 million at the gala via tickets, sponsorships and silent and live auctions.
In brief remarks as he entered the event, Doug Ulman, chief executive of the foundation and a cancer survivor, told reporters that the event was about raising money and continuing the organization's work to combat cancer, not about the doping allegations.
Early Sunday morning, Armstrong is expected to address nearly 4,000 cyclists before the start of the Livestrong Challenge, an annual fundraising race that starts in the heart of Austin.
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