In heartbreaking news, Beastie Boys member Adam Yauch (aka MCA) passed away at the age of 47 earlier today (May 4). Upon hearing of his death, many musicians in the rock community have expressed both shock and sadness via Twitter. Yauch lost a three-year battle with cancer, and his loss weighs heavily on the rock community. The news comes only weeks after the Beastie Boys were inducted into the Rock and Roll Hall of Fame. Such rockers as Slash, Linkin Park, Papa Roach, Disturbed's David Draiman, Limp Bizkit's Fred Durst, Lamb of God's Randy Blythe, Motley Crue's Tommy Lee and more have offered their condolences. We at Loudwire are devastated, as well. Below are the reactions from some of Yauch's musical peers: