Seth Rogen and Will Reiser, friends and “50/50” collaborators. (Marvin Joseph/WASHINGTON POST)

The commercials for “50/50” — the new dramedy about coping with cancer that opens in theaters today — make it clear that this story of a 27-year-old (Joseph Gordon-Levitt) who discovers he has a potentially fatal disease is based on a true story. And that true story is based on the experiences of “50/50” screenwriter Will Reiser, who was diagnosed with cancer at the age of 25 and survived it with the support of friends like Seth Rogen, who co-produced and stars in the movie opposite Gordon-Levitt.

In this longer story about “50/50,” I noted that the two first struck up a friendship in 2004, when they worked together on Sacha Baron Cohen’s ”Da Ali G Show.” But during my interview with Rogen and Reiser, I learned much more about the behind-the-scenes experience on that HBO comedy/gotcha! interview series.

Rogen, who worked as a writer on ”Ali G,” noted at one point that his boss only found out after hiring him that he had acting experience on TV shows like ”Freaks and Geeks” and “Undeclared.”

“The ‘Freaks and Geeks’ DVD came out while we were doing the show and Sacha had no idea I was an actor at all,” Rogen recalled. “I remember he came in with an ad for the DVD release and was like, what the [bleep] is this? I was like, I was on a TV show. He said, I had no idea you were an actor at all. I was like, yeah, most people don’t. And there’s a good chance I never will be.”

Here are more extracts from my interview with Reiser and Rogen, the friends who made “50/50,” as they remember their first working experience together, when they both reported to Baron Cohen.

Will Reiser, who worked as an associate producer on “Ali G”: They were writers. I wanted to be a writer. I wanted to be in that writers room. I was jealous of them for sure. I was envious.

Seth Rogen: We had a much more fun job. (Laughs)

Reiser: Our rooms were separated by a giant glass window.

Rogen: So we could literally see —

Reiser: — We just saw each other all day. And they’d be in the room — the five writers, and Sacha, in the room — laughing all day. And I’d be on the phone, trying to convince, you know ... I’d be on the phone trying to convince people to go on the show, which was in­cred­ibly stressful. It was this giant ruse. I was always under high levels of stress.

Rogen: If he didn’t get the people —

Reiser: Yeah, it reflected poorly on me.

Jen Chaney: And it would mess up your bits.

Rogen: And it messed up our bits. That’s what would screw us also. Sometimes we didn’t get the bit so like —

Reiser: — We need a psychic medium!

Rogen: Or then we’d get one the next day sometimes, and then we’d have to frantically write the bits in time to make the appointment, essentially.

Reiser: But nothing they did was nearly as frantic as what I did.

Rogen: No, not at all. I gotta say, he probably had to scrunch to do it every time. Writing jokes — you know, that’s never that stressful.

(Later in the interview) Chaney: I understand that Seth, you and other people on “Ali G” noticed that Will looked rundown a lot when he was working on the show.

Rogen: He did.

Reiser: I looked like [expletive] We all thought it was the stress.

Rogen: We thought it was the stress of the show.

Reiser: Because I wasn’t sleeping.

Rogen: I mean, our hours were bad, too. We worked really long hours on the show. As far as writing goes, we worked from 8 a.m. until 10 or 11 p.m. pretty much every single day, at least. So you know — and I think we all looked up to Sacha so much that just being around him was stressful. Just his presence was kind of stressful at the time. Now it’s just fun to see him. But he’s intense.

Reiser: He’s such a perfectionist. That show is so good because he works so hard and he takes —

Rogen: That show is not effortless.

Reiser: He’s one of the hardest working people I’ve ever met.

Rogen: Yeah. Me, too.

So that’s what we thought it was. We thought that some people just show the symptoms of that stress differently. Me and Evan [Goldberg, Rogen’s writing partner] would drink a lot, probably. And Will just looked terrible.

Reiser: What was funny, though, was we worked on season two. And season one, the woman who had my job, I guess, had a brain tumor.

Rogen: Are you serious?

Reiser: So when I got cancer, everyone was like, Sacha, what are you doing to these people?

Rogen: It’s like working in Chernobyl.

Reiser had surgery to remove a massive tumor in his back in 2005, several months after his stint on “Da Ali G Show” ended. He has been in remission for six years.