From PEOPLE Magazine Click to enlarge
Marlee Matlin was in the middle of a June business meeting when a text from her brother drove every other thought from her head. "Dad took some tests," it said. "He has excess cells in his bone marrow." Reeling, she texted back the dreaded question: "He has cancer?"

Just six months earlier Matlin's sister-in-law Gloria had been diagnosed with breast cancer and was undergoing chemotherapy. In 2004 her mom, Libby, 80, had a lumpectomy to remove a malignant tumor from her breast. Now Don Matlin, 80, a gregarious retired car salesman who taught his deaf daughter that nothing was out of reach-and cheered as she won the Academy Award for her performance in the 1986 film Children of a Lesser God-was facing the fight of his life after being diagnosed with stage 3 multiple myeloma, a cancer of the bone marrow. "My heart sank," says Matlin, 45. "But I want to stay strong to help take care of him."

On Sept. 10 Matlin will take part in Stand Up to Cancer, a fund-raising special airing live on ABC, CBS, FOX, NBC and several cable channels. She especially hopes to reach deaf Americans, who often struggle to get promptly diagnosed and treated. "Get your exam, see your doctor, be aware of your body," says Matlin, a 2008 Dancing with the Stars alum.

Don had been suffering from sciatic pain, but when he went in for spine surgery, a routine blood screening led to the life-threatening diagnosis.

"I feel good that they found it and bad that I got it," says Don, who has begun chemotherapy and is taking the drug thalidomide. Matlin stays on her dad's case, making sure he takes his pills and exercises, and shares updates on her four kids, ages 6 to 14, with husband Kevin Grandalski, a police lieutenant. "Marlee's tough," Don says. "She's in my corner-and that's helping me get through this."

FOR MORE INFORMATION, GO TO STANDUP2CANCER.ORG