At 60 years old, an age she freely admits, Mary Steenburgen has had an amazing career. She's an Oscar-winning actress, an award-winning song writer and has starred in so many projects that are a major part of pop culture from 'Elf' to 'Back to the Future III' to 'Step Brothers.' She continues to work and, maybe most impressively, isn't just playing the grandma in a movie. She's the romantic lead in a movie opening today, 'Last Vegas' with Michael Douglas, Robert De Niro, Morgan Freeman and Kevin Kline.

We caught up with Steenburgen to talk about her impressive career, the 'Step Brothers' outtakes, a return to 'Curb Your Enthusiasm' and how nerds keep coming up to her wanting to talk about 'Back to the Future' 23 years later.

I know it seems cliched to say this, but it does seem that you all had a really good time making this movie.

It was absolutely as much fun as it seems, maybe moreso even. First of all, we didn't know each other at all. I had met each of them before, but the only ones among us that had worked together at all were Kevin and I briefly in 'Life as a House.' I think we had two scenes together. I don't know what they thought about each other, but they were all on my fantasy wishlist of people I wanted to work with someday. So, that was some kind of crazy Vegas jackpot that I got all of them in one movie. And also for me, to play a part like this that I haven't played in a very long time...that felt pretty lucky.

What instantly happens on Day One, a bunch of legends - on their part - walked into a room to read together and one minute into it, it was fellow actors who had a deep respect for each other and actually wanted to know how each other worked. In all those moments when we were this little island with this sea of Vegas around us, somehow we managed to focus on each other and talk about our lives. We discovered so many weird parallels and all of us were in New York City around the same time. I'm a little younger than these guys - I'm 60 - but there was still so much in common about family, actor stories, stage stories and various people we had all worked with. I couldn't get enough of it. One of the things about being this age is, you're not worrying yourself about what your next job is. You have kinda proven a certain amount to yourself, so what you learn is the art of enjoying the moment and the five of us did.

Did all five of you come to this project together, or had they all been cast before you came aboard?

They were set. I had to fight for the part. It was a big question, who is she gonna be? Everyone my age, within 15 years, wanted the part and I don't blame a single one of them. I knew I would be very blessed and lucky if I got it. In some ways, I fought for it. I knew the singing would be a huge part of it and I was terrified of that. I'm a very musical person. I write music, as a staff writer for Universal Music Group and I have since 2007. I've never talked about it publicly because I wanted to earn the right to be in the same room as the great writers I write with and not shoot my mouth off because I'm an actor. It's really important to me and I really care about it.

So, the first thing I did was to write a song with Jared Crump and Jeremy Spillman called "Cup of Trouble," a jazz song for this film and for myself to sing. I worked at it and recorded myself and sent that to them. I think that was the first way of proving myself to them. I wrote them, "I understand who she is. I understand what it is to have dreams at this age that you haven't fulfilled yet. And I understand to have music in you and the fear of dying with music still in you. I wrote a lot of things and sent them to [director] Jon Turtletaub and when I finally was in that room with them, I felt like I deserved to be there.

You mentioned before that at your age you don't feel like you have to prove anything to yourself any more --

Oh, I wouldn't say that I don't have anything to prove. I actually still feel like I have to prove things to myself. Sorry about that. I do feel that way. What I meant was that, with the guys, we had the luxury of not having to focus on building a career and just focusing on the moment. Do I feel like I still need to prove myself? Absolutely. And I want to feel that way and I like that. If you're not growing, you're dying and I'm not ready for that. I liked with music that it was scary.

Your career has been remarkably--

Weird (laughs)?

Well, no, but I guess that could work too. But, the longevity of your career has been remarkable, especially when you hear a lot of actresses say that there are no good roles for older women. To what do you attribute that success?

I started at 24 and I'm 60 now, but I'm bad at math. Part of that, I'm sure I can't answer because I honestly don't know. I think I've tried to not know so much about how people hold me because I never want to be stuck in either people's idea of me, or my idea of me. I wanted there to always be something around the corner that I haven't done yet or something that I could try. Maybe I sitll feel very hungry. I feel satisfied and grateful, but I still feel hungry. Techncially, part of the secret is comedy. I'll never be someone like Tina Fey or Amy Poehler (I have girl crushes on both of them). I'll never be funny that way, but I did comedy improv a million years ago when I first started in New York and I couldn't get cast in anything. The big thing I learned was that the only way I could be funny was Mary Nell Steenburgen from Newport, Arkansas. I couldn't be funny the way people I admired were funny. I think technically the fact that I'm not afraid of comedy has served me well. Sometimes now, people forget that I can do drama! But, if they're gonna forget one, I'd rather them forget that to be honest. I love being a part of that. People can sneer at 'Step Brothers' but I couldn't have had more proud of that movie.

I would imagine that with all your success, when people stop you in public, the majority of the time, they're talking 'Step Brothers.'

I'm mostly recognized by guys your age and younger. Mostly young men and it's almost always 'Step Brothers.' Or, people are a little older but also 'Elf.' And then a certain amount of nerds for the 'Back to the Future' films. Now, it's a long time ago, but there are "film buffs" who are super obsessed with it. I just did a piece with Entertainment Weekly the other day and I was shocked because it was the 20th anniversary of '[What's Eating] Gilbert Grape.' And people are still obsessed with that movie, so we did a piece on that. That's another one that really hit people and people really relate to it. It's funny what people see, but that's someone else's job. My job is to take the words that a writer put on the page and make them as alive as possible.

Speaking of comedy, do you have any plans to return to 'Curb Your Enthusiasm' or the rumored 'Step Brothers' sequel?

I love Larry dearly. And doing 'Curb' is just like hanging out with Larry. They keep saying that we're going to do a 'Step Brothers 2' but they did just do 'Anchorman 2,' which encouraged me because it had been some years in between. But, would I? I would be there Day One, with the biggest smile on my face. I love those guys and the joy of working with them. It's hard for me though, because I'm a terrible giggler. You can see my laughing all throughout 'Step Brothers' and I said to [director] Adam McKay, "Why'd you leave that in the movie, you can see me laughing?" And he said, "Yes Mary, we can see you laughing and I don't have a take where you're not."

The outtakes from that movie are fantastic.

I wish they put all of the outtakes from Will [Ferrell] and I in the car online. I know they put a couple of them out there. When we shot that scene where I'm driving him and he's in the backseat, the scene was supposed to take two hours to shoot and five hours later we didn't have one complete take. One or both of us messed up every take. Will was out of control, asking me about my sex life. It was completely ridiculous.

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