Kobe on tweet: I had to respond

Kobe Bryant welcomes challenges, which explains why he chastised a fan on Twitter for using a homophobic slur.

"It's the right thing to do," Bryant told ESPN.com Tuesday. "I couldn't help myself. I saw it, I was like, 'I can't help myself. I have to respond.' "

On Sunday night Bryant tweeted: "Just letting you know@PacSmoove @pookeo9 that using 'your gay' as a way to put someone down ain't ok! #notcool delete that out ur vocab."

Bryant knew he would have people questioning his moral authority to make that statement because he was fined $100,000 in April for using a gay slur in a nationally televised game, an incident NBA commissioner David Stern called "offensive and inexcusable."

After receiving a technical foul in a game against the San Antonio Spurs, Bryant yelled at referee Bennie Adams before muttering a gay slur while sitting on the bench. The episode was caught on camera during TNT's national telecast.

Bryant apologized a day later, saying he did not mean to offend anyone.

A year earlier, the NBA had released a public-service announcement featuring Jared Dudley and Grant Hill in which they denounced using "gay" as a slur. Athlete Ally announced this week that Denver Nuggets forward Kenneth Faried would be joining the organization, which seeks to end homophobia in sports.

Bryant made a spur-of-the-moment decision while looking through the mentions on his Twitter feed.

"Some people probably wouldn't have responded just because they're afraid of the backlash you might get," Bryant said. "I responded and told him to delete that out your vocab.

" 'But you said ...' Yeah, I did say it. That doesn't mean I'm going to say it again. I think it's important to have that kind of engagement.

"A lot of times, especially as celebs, people want to put you in a box because this is what you were at the start. You evolve. You change as people."