Anderson Silva "the greatest mixed martial artist ever." has a professional boxing record record of 1-1-0
Plenty of kickboxers have been succesful boxers :conf If MMA guys could box then they would & make a lot more $. Sadly they cant & prefer to wrestle with other men in lycra
Chris Lytle is probably the best example - http://boxrec.com/list_bouts.php?human_id=121346&cat=boxer Plenty of MMA fighters have fought professionally, but afaik there hasn't been no-one has crossed over and achieved significant success. Most generally use it to sharpen their striking skills, rather than completely switching careers. The chances of an established MMA fighters becoming a world class boxer are pretty slim. It's difficult (but not unheard of) for fighters who start in their mid 20s to become successful. Boxing also requires a much more specific set of attributes than MMA, where there are more routes to success. The chances of a successful MMA fighter also having world class boxing talent are also slim.
Highly unlikely, because most of MMA fighters w/c has other forms of striking as their base/fundamentals. May it be Muay Thai, Karate or Taekwondo and it completely ruins their boxing form. Look at Anderson Silva for example. As exceptional in striking as he is, his boxing form is below mediocre. Not to mention the habits.
Nobody important. Just THE SAVIOUR TO THE HEAVYWEIGHT DIVISION Kimbo "Meat" Slice. Run Klitschkos Run.