Celeb: The ultimate slash collector, “America’s Got Talent” host, rapper, actor, comedian, DJ, TV producer and Mariah Carey’s husband, Nick Cannon, whose second studio album, “White People Party Music” was released April 1.

Cause: The Lupus Foundation of America’s eighth annual “Walk to End Lupus Now” event in Washington on Saturday morning. Cannon was diagnosed with the auto-immune disease in 2012 and has been outspoken about raising awareness ever since. He created a Web series — “The NCredible Health Hustle” — documenting his diagnosis and doctors visits.

Scene: The 33-year-old father of twins was missing the cheetah print coif he debuted on Instagram last month. But have no fear, Cannon, who flew into D.C. from Los Angeles on a red eye and arrived at the scene on Pennsylvania Avenue just moments before revving up the crowd of 4,000, was equal parts showman and supporter. Dressed in a sleeveless purple “Walk to End Lupus Now” T-shirt, he told us, “Honestly I feel like I’m here to be a part of the community than be that one to stand in front. I’m truly here in support more than anything.” And in the time it took for a group of girls to ask for his photo, Cannon quickly turned on the energy and his dimples. On stage he was confident and knowledgeable — pushing for more awareness, more research and a cure — then he slid back into his mix tape roots, shouting “Let’s Go” to amp the crowd for the journey ahead.

Sound bite: “I was actually going to dye my hair purple but it turned out like this fuchsia.”

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