Singer and actress Bernie Nolan has died aged 52 after a long battle with cancer, her publicist said.
The star was told in 2010 she was clear of breast cancer, but last year discovered it had spread to her brain, lungs, liver and bones.
A spokeswoman for the family said: "Bernie passed away peacefully this morning with all of her family around her. The entire family are devastated to have lost beloved Bernie, a wonderful wife, adoring mother and loving sister; she is irreplaceable. They kindly ask people to respect their privacy at this difficult time."
Bernie shot to stardom with her singing sisters The Nolans.
The group, best known for 1979 hit I'm In The Mood For Dancing, sold millions of records around the world and enjoyed success with songs such as Don't Make Waves, Attention To Me and Gotta Pull Myself Together. They became huge in Japan, where they are said to have sold more records than the Beatles, and also supported Frank Sinatra.
Nolan was born into a showbusiness family - her parents Tommy and Maureen were singers - and the family group learned their trade singing in pubs and clubs. She once said: "It got to the stage where they didn't talk about whether the new baby was going to be a boy or a girl, but whether they could sing."
The girls' father Tommy became their manager and after his death Anne, the eldest sister, revealed he had sexually abused her from the age of 11. Bernie quit the group in 1994 and made a name as an actress appearing in Brookside and The Bill. The Nolans reunited in 2009 for a sell-out tour, which led to a dispute with Anne and another sister, Denise, who were excluded.
Nolan, who gave birth to her daughter Erin in 1999, also took part in Channel 4 series The Games and ITV's Popstar to Operastar. On stage, she performed in Blood Brothers, Flashdance The Musical and the UK tour of Chicago The Musical in 2012 as well as a touring production of Calendar Girls.
Nolan, who married drummer Steve Doneathy in 1996 and whose first daughter Kate was born stillborn in 1997, was told she had breast cancer in 2010, becoming the third sister to have the disease.
Chris Askew, chief executive of Breakthrough Breast Cancer, said he was "deeply saddened" by the news. He said: "Bernie was a truly inspirational woman who became a part of the Breakthrough family after her first breast cancer diagnosis in 2010. We were devastated to hear that her breast cancer had returned in 2012. Her spirit and determination to try and fight the disease spurred us all on and will continue to do so. Our thoughts are with Bernie's husband, daughter, family and friends at this time."