When Mel Brooks rewired "Young Frankenstein" for Broadway, he transplanted the comedy's best gags to the musical.

Think Dr. Frankenstein (the Gene Wilder role) pronouncing his name "Fronken-steen" since he loathes his crackpot grandfather. His tangles with his uptight fiancee (Madeline Kahn ) and curvy lab assistant (Teri Garr) and Igor's (Marty Feldman's) migrating hump.

"Puttin' on the Ritz?" That was a no-brainer.

The doctor-monster tap duet, performed by Wilder and Peter Boyle, defined -- and hilariously undermined -- the whole man-plays-god premise. It also gave the spoof of classic horror films a life of its own. "Young Frankenstein" (1974) is ranked 13th on the American Film Institute's list of the 100 funniest movies.

"It's such a preposterous notion -- that a mad scientist wold take his first specimen he has groomed to adapt to society and put him in a big showy musical number," said Roger Bart, who created the title role on Broadway.

"The audience members who have seen the movie flip out," said the stage vet ("You're a Good Man, Charlie Brown," "Producers"), reprising his role on tour. "And for those who haven't, it's the most memorable moment."

It's heartbreaking, too -- a subtlety sure to dawn on theater-goers who catch "Young Frankenstein" Tuesday through Dec. 13 at the Cadillac Palace Theatre. The Monster (Shuler Hensley, who created the hulk on stage) is desperate to please his father figure. And bombs.

A warped reimagining of Mary Shelley's thriller, "Young Frankenstein" earned mixed reviews during its New York run from Nov 8, 2007, to Jan 4, 2009. Brooks penned the music and lyrics, co-writing the book with Thomas Meehan ("Hairspray") and tapping "Producers" pal Susan Stroman as director.

He also famously slashed the cast's wages last year when the recession gutted ticket sales, which may explain the absence of principals Sutton Foster (Inga), Megan Mullally (Elizabeth) and Andrea Martin (Frau Blucher) on tour.

Yet the "Puttin' on the Ritz" routine spawned raves. Brooks and Stroman expanded the Irving Berlin chestnut into an eight-minute showstopper, a spoof of Fred Astaire's big dance scene in "Blue Skies" (1946). The Doc and Monster hoof it up in tophats and tails backed by a chorus line of the undead.

Like the original, the stage number tips its hat to the old Hollywood musicals. It also pays tribute to the genius of Wilder and Boyle. The former insisted on the scene. He and Brooks argued, with Brooks likening his star to an attack dog. "To appease Gene, he said, `OK, we'll do it,'" said road director/swing James Gray. "Then he said, `Oh, my God, it is perfect.'"

For his part, Boyle ("Everybody Loves Raymond") yanked heartstrings as his Monster gamely tapped, flailed and swung his cane. The Second City alum ad libbed his near-mute brute's strangled cries of "Puinnnn' on the rizzzz."

Hensley -- a hulking straightman in greenface who stand 6-foot-7 in his platform boots -- "can hear mumbles" as the big number approaches. "They're just waiting for the Monster (to start slurring), 'Puinnnn' on the rizzzz,'" he said.

For the Monster, it's his turn "to have fun and break loose. My mom was a ballet director, so I know the whole feeling," he said. "When you can't express yourself in any other way, you gotta dance! The Monster gets a chance to do that."

Yet Bart sees the much-parodied song-and-dance number as a turning point. His character realizes that, like a pushy stage parent, he's set his pride and joy up for failure. The walking grabbag of body parts becomes his son.

"Can you imagine the poor guy?" said Bart, a real-life father of two. The Monster's "been taunted a bit by the villagers, and he's never stood in front of a theater with people screaming at him. It reminds me of the early scenes in 'The Elephant Man.' He's treated like a circus act."

It's a classic Brooks moment, fusing silliness with self-awareness. It also brings down the house, not unlike a certain "Producers" number. "Puttin' on the Ritz "is our 'Springtime for Hitler,'" Bart said.

"Young Frankenstein," by Mel Brooks, Tuesday through Dec. 13

Where: Cadillac Palace Theatre, 151 W. Randolph St., Chicago

Cost: $30-$95

FYI: (800) 775-2000 or broadwayinchicago.com