Robert LuPone's earliest memory of performing with his actress sister Patti LuPone is reflected in a photo "that I still have of us when I was in, I think, sixth grade. We were doing a PTA recital. There was a tap dance that we did together, and I have her in a lift. That's the picture. I'm wearing a white, fake silk [shirt] and white satin pants with tap shoes, and I think she's wearing a dress with sequins and she had no front teeth."

His sister's memory stretches back a bit further: "Our father [Orlando Joseph LuPone] was principal at the time of the only elementary school in Northport, where we grew up, and he started an extra-curricular program. One of the activities was dancing. I was enrolled when I was four, and at my first concert I fell in love with the audience, and Bobby fell in love with my hula. So we both started dancing at four and seven years old."

Four decades later, the LuPone duo may have put away their tap shoes, but both actors remain indomitable forces onstage and off. Robert, a former Martha Graham-trained dancer and co-founder of New York's MCC Theater, is set to co-star in the critically-acclaimed revival of Arthur Miller's A View from the Bridge when it reopens at the Neil Simon in April; seven blocks over at the Booth Theatre, his younger sister, Patti, is currently receiving the kind of reviews one dreams about in David Mamet's newest play, The Old Neighborhood.

In fact, in his New York Times review, Ben Brantley exclaimed, "You will be stunned by the naturalistic fire Patti LuPone delivers here. . .she finds conflicting layers of past and present selves in practically every line, emerging as both a loving matriarch and wounded adolescent, sentimental and devastatingly clear-eyed." That naturalistic fire has been present in every work in which the singing actress has appeared, from her breakout, Tony winning run in Evita to her Olivier winning performance in Les Miserables and her last Broadway stint as Zoe Caldwell's replacement in Terrence McNally's Master Class. Similarly, her brother has triumphed onstage in the original production of A Chorus Line -- for which he received a Tony nomination as Zach -- and when he tried his hand in television, he garnered an Emmy nomination for his portrayal of another Zach, Zach Grayson, on ABC's "All My Children."

Earlier this season, Robert succeeded Stephen (Angels in America) Spinella in the role of Alfieri, a veritable one-man Greek chorus, in the Arthur Miller tragedy, which was so successful during its limited Roundabout run that it will reopen at the Neil Simon next month. Robert explains that as a replacement, he had only 20 onstage hours before being thrust in front of an audience. "I call it learning a role on your feet," he laughs. "Quite frankly, I have to credit Anthony LaPaglia [who stars in the Arthur Miller tragedy] because he was one of the most generous and kind actors I've ever come across." It was also a revelation to Mr. LuPone to discover just how gifted a writer Arthur Miller is: "Like every other person in the theatre who was ignorant, I thought Tennessee Williams was the better writer. And I'm tremendously surprised and relieved to say that Arthur Miller is as good if not better than Williams. This play is magnificent. It's a joy to do."

Ms. LuPone is equally effusive about David Mamet, the playwright of her current triumph. LuPone has a long history with Mamet, which dates back to 1975 and her final year with John Houseman's Acting Company, a group of Juilliard-trained actors who traveled the country performing in both classic and original plays. Mamet had been commissioned to write a play during that year, but by the end of '75, "the company broke up, the play was never written, and David picked me up as an actor, and I started working with him in 1976."

LuPone says she feels an affinity for his writing style, a style that creates as much drama with the use of the pauses between words as the actual words themselves. Although she stars in just one of the play's three vignettes, it is her image as the ironically named Jolly, the protagonist's sister, that one leaves the theatre with, a woman struggling with the emotional scars of her childhood. When asked whether she finds her role draining, LuPone explains, "A beautiful, well-written role it can't possibly drain you. If you have a lousy part, something that taxes the actor to make work, that's draining. But if you have well-written roles, you can only be exhilarated by the release of it and by the ability to grow in it."

Both LuPones have also managed extremely varied careers; viewed together, this somewhat mind-boggling list of credits includes dramatic, musical, film and television actor; concert singer; dancer; director; and producer. Neither, however, has actively sought such versatility: "An actor goes where the work is," Patti relates with her trademark laugh. Her brother concurs and elaborates: "I just followed the next job. My real kick is to try to evolve personally, and I think that's one of the guiding principles . . . but I would always try to keep two things in mind. One, what the next job was depending on what I needed financially and, two, what the next job was in terms of my own personal interest in art."

Such personal growth has been evident in each actor's career. Patti has not only become one of the theatre's leading dramatic and musical actresses, but she also maintains a thriving career as a solo concert artist. Currently she is preparing a new act with Scott Wittman, the director of her last one woman concert, Patti LuPone on Broadway, and her new repertoire boasts work by such disparate composers as Billy Joel, Rupert Holmes, Irving Berlin and John Bucchino. "There is original material, some pop material," Patti explains, "and some classic Broadway show tunes." Meanwhile, her brother added producer and director to his list of credits as co founder of MCC Theater a decade ago. "We do three plays a year," Robert remarks. "We work on new plays and generally we work with new writers, writers who have one, two or three new plays under their belts. But because of my partner Bernie Telsey's casting business, we get great actors . . . and we've elevated the theatre from an idea in my apartment to an existing, recognized, industry-driven, high-standard professional theatre."

There is a third LuPone sibling, Bill -- Robert's twin -- who abandoned show business in high school to become a teacher, now living in Vermont. However, looking back, both his brother and sister realized early on that performing was their destiny. "I stood on that stage, downstage right, in a black leotard, black jazz skirt, black tap shoes," Patti remembers, "and fell in love with the audience, and I never looked back." "I had such an acceptance in [dancing]," Robert adds, "and you travel toward your acceptance. I was accepted at seven years old, so I just continued being accepted. And when I wasn't accepted I would change my venue and find another venue such as acting or producing." Robert no longer dances -- "It's a young man's profession" -- but would be open to choreographing and admits, "I found an agility and a natural gift in dance, [but] I found myself in acting."

It's evident that the two have a mutual respect for each other's work. "When I first saw Bobby dance at Juilliard," Patti says, "it was just mind-blowing. Bobby was a phenomenal, phenomenal dancer." Although there was a period when the two stopped speaking "it had a lot to do with family dysfunction and competition," explains Robert the two are again close and often offer each other advice about their performances. "I'm happy to say that we've truly worked through [any problems], and it's so interesting to be so close again as we once were. . .What happened is a result of [Patti having] her own family and being a mother herself and both of us maturing and wanting to reconnect. The devotion we had as kids has been rekindled. . .and we're both on Broadway at the same time, and that hasn't happened since A Chorus Line 22 years ago."