ON STAGE -- April IT KEEPS ROLLIN' ALONG: Save for a show-stopping Joel Blum, a returning Lonette McKee and a Tony-winning Gretha Boston, Broadway's Show Boat is carrying a whole new cargo of stars: John Cullum as Cap'n Andy, Carole Shelley as Parthy, Sarah Pfisterer as Magnolia, Hugh Panaro as Gaylord, Beth Leavel as Ellie, Fred Love as Steve and Andre Solomon Glover as Joe. . . . The producers of How To Succeed in Business without Really Trying presented John Bolton a bottle of champagne for going on so brilliantly for the ailing John Stamos. Even better, and sweeter, they let him do the lead till Matthew Broderick finished filming The Cable Guy with Jim Carrey and resumed his Tony-winning role opposite main squeeze, Sarah Jessica Parker.

CLEANING THE BIRDCAGE: At the Drama League winter-benefit salute to director Jerry Zaks, the hot! hot! hot! Nathan Lane did a Sondheim ditty from their forthcoming Forum, and it wasn't his first. He also did a Sondheim in The Birdcage, the otherwise nonmusical U.S. film version of La Cage aux Folles. Nary a Jerry Herman tune was used, and two new Sondheims were (a cappella, at that!). Ironically, Sondheim's Pulitzer Prize-winning Sunday in the Park With George lost the Best Musical Tony to Herman's La Cage. . . . Mike Nichols, who directed The Birdcage, is spending the spring onstage as a performer in London in The Designated Mourner, a play written by Wallace Shawn (who's normally an actor) and directed by David Hare (who's normally a playwright). When he was asked if there was any chance that he'd do the play on Broadway, the ever-succinct Nichols replied, "None."

CHANNING STICKS AROUND: Bradway has said "Goodbye" to Hello, Dolly! but not to Carol Channing, who's sticking around a while, spreading that star stuff about at various functions before she takes the show abroad for its farewell tour. She glittered up a TDF to-do in which Alvin Colt and Miles White became the first recipients of The Irene Sharaff Lifetime Achievement Awards. Then, she and Victor/Victoria's Julie Andrews teamed up for a Broadway Cares/ Equity Fights AIDS benefit screening of their 30-year-old song-and dancer, Thoroughly Modern Millie.