The adult film industry certainly has its highs and lows. On the plus side - constant boning. On the minus side - constant boning. And there is the stigma attached to adult films, which can lead to negative repercussions in later life, and if you want a successful mainstream showbiz career, it's almost impossible.

For every success story like Traci Lords, there are dozens of adult film actors who were never given the chance to spread their wings in Hollywood.

Today is Sean Paul Lockhart's 28th birthday, so let's take a look at him, and four other gay adult stars who have tried to make that mainstream crossover.

Sean Paul Lockhart

ADULT FILM NAME: Brent Corrigan

AGE: 28

BEST KNOWN ADULT FILMS: The Velvet Mafia, The Porne Ultimatum, Getting Levi's Johnson, The Twin Dicks Of Hazzard

MAINSTREAM CAREER: The Big Gay Musical, Another Gay Sequel, Judas Kiss, Chillerama, Triple Crossed, High School Musical

As Brent Corrigan, he used his youthful exuberance and undeniable resemblance to Zac Efron to become one of the most popular adult film stars of his generation. He began to branch out into mainstream films with a role as "Stan The Merman" in 2008's Another Gay Sequel and a bit part in Milk.

That led to bigger roles in The Big Gay Musical and starring roles in Judas Kiss and Triple Crossed (which he also directed). He has been back to adult films, but continues his mainstream success. Here's the trailer for his 2013 film Truth

Dylan Vox

ADULT FILM NAME: Brad Benton

AGE: 39

BEST KNOWN ADULT FILMS: My Overstuffed Jeans, Desperate Husbands, Sexual Urban Legends, Deep South: The Big And The Easy

MAINSTREAM CAREER: Dante's Cove, The Liar, Battle Of Los Angeles, Mega Shark vs. Crocosaurus, Apocalypse Pompeii, Super Cyclone, Titanic II, Virus X

Starting in 2001, Dylan (as Brad Benton) spent five years in adult films, but he's managed prolonged success outside adult films in "B" movies (anyone who loves Syfy Channel movies knows who he is), as well as starring in the Here! series Dante's Cove and The Lair. Here's his mainstream reel.

François Sagat

ADULT FILM NAME: Azzedine, François Sagat

AGE: 35

BEST KNOWN ADULT FILMS: Humping Iron, Alpha: Centurion Muscle II, Arabesque, Hole Sweet Hole, Escape From San Francisco, François Sagat's Incubus

MAINSTREAM CAREER: Saw VI, L.A. Zombie, Man At Bath, Multinauts

Francois began his career in modeling, and segued into adult films, where he became one of the biggest stars of the mid-2000's, using his brawn and his trademark scalp tattoo to stand out. He announced his retirement from adult films in 2013, and announced his own clothing line, KICKSAGAT.

Glenn Soukesian

ADULT FILM NAME: Colton Ford

AGE: 52

BEST KNOWN ADULT FILMS: Gang Bang Cafe, Head Games, Aftershock, Conquered

MAINSTREAM CAREER: The Lair, Another Gay Sequel: Gays Gone Wild!, The Next Best Thing

Colton's adult film career was brief, but memorable, which he used a springboard for his true passion, music. Colton has released numerous studio albums, and his singles have been club hits worldwide. Here is "All My Love" from last year's album The Way I Am.

Gregory Grove

ADULT FILM NAME: Matthew Rush

AGE: 42

BEST KNOWN ADULT FILMS: Whorrey Potter And The Sorcerer's Balls, Aftershock, The Velvet Mafia

MAINSTREAM CAREER: Third Man Out, Another Gay Movie, L.A. Zombie

Matthew has been acting in adult films since 2001 (his retirement from adult films in 2011 lasted three months), but he has branched out into mainstream films, performed onstage in such hits as Psycho Beach party, and competed in the Gay Games in Amsterdam and Sydney Australia.

Oh, and his character in Whorrey Potter And The Sorcerer's Balls? Voldemorecock.

Here is Matthew with Brent Corrigan in "How To Use A Condom."