Madonna says Adam Yauch, the Beastie Boys rapper who died Friday, was one of a kind and that the group was important to her musical history.
The singer says the seminal hip-hop group was "integral to the musical revolution that was happening at the time."
Yauch's representatives confirmed that the rapper, also known as MCA, died Friday morning in New York after a nearly three-year battle with cancer.
Madonna says she was sad to hear of Yauch's death and asked God to bless his family.
The Beastie Boys opened for Madonna on tour in the 1980s, and the group was inducted into the Rock and Roll Hall of Fame last month.