CINCINNATI -- Jeanine Duncan, the matriarch of a baseball family, lost her battle with a brain tumor on Thursday. She was 64.

Jeanine, the wife of longtime pitching coach, Dave, and mother to Major Leaguers, Chris and Shelley, had been diagnosed with Stage IV glioblastoma, a malignant brain tumor, in August 2011. She underwent surgery at Duke Medical Center, but the tumor had spread too much to allow for a full removal.

Jeanine had continued her fight since, alongside her husband. Upon Jeanine's diagnosis, Dave took an immediate leave of absence from the Cardinals, for whom he had served as pitching coach since 1995. Dave -- at his wife's insistence -- returned to the dugout for the club's playoff run in 2011, and Jeanine was among those in the Busch Stadium stands for the Cardinals' Game 7 win over the Rangers in the World Series.

After the postseason, Duncan permanently stepped away from his duties with the Cardinals. He had been a professional pitching coach since 1978, with his longest stints coming alongside manager Tony La Russa in Oakland (1986-95) and St. Louis (1996-11).

"There was never a question how much he loved his family," St. Louis manager Mike Matheny said of Dave. "For a man who was short on words but never short on intensity, whenever he began to talk about his family, he lit up. He didn't care to hide it. He was very proud of his family and rightfully so."

"She kept balance in their family," Cardinals pitcher Adam Wainwright said. "So many moms are like that, but in their family, she was the rock. And she was loved around our clubhouse, there's no doubt about that. I think what she did so great was that she knew the baseball lifestyle, and when Dave came home and Chris came home and Shelley came home, she was that shoulder to lean on."

Amid Jeanine's own fight, the Duncan family entered another when, in October 2012, Chris was also diagnosed with glioblastoma. Chris, 32, was an outfielder for the Cardinals from 2005-09 before transitioning into a second career as a sports talk radio personality in St. Louis. Chris underwent brain surgery soon after the diagnosis and returned to work earlier this year.

Through it all, Shelley has continued his professional playing career. Drafted by the Yankees in the 2001 First-Year Player Draft, Shelley has also made career stops with the Indians and Rays. Tampa Bay designated him for assignment in late April, and Shelley is playing for the organization's Triple-A club.

Dave and Jeanine made their home in Kimberling City, Mo., where, together, they would listen to Chris' radio show and watch Shelley's game. Dave took Jeanine to Duke every two months for followup exams and shuttled her back and forth to weekly treatments and biweekly chemotherapy.

"We're just each others' rocks," Jeanine told MLB.com earlier this year.

"Jeanine fought her illness with courage and dignity," the Cardinals said in a statement released Friday. "She will always be remembered as a devout wife and mother who supported her baseball family with passion and encouragement."

The Cardinals announced that services for Jeanine will be held at Cathedral Basilica of St. Louis at 11 a.m. CT on June 15.