Adam 'MCA' Yauch of the popular and pioneering rap group Beastie Boys, died today (May 4) after a nearly three-year battle with cancer. The bold use of Led Zeppelin, Black Sabbath and Aerosmith samples on their first album, 1986's 'Licensed to Ill,' helped introduce a whole new generation to hip-hop. The group would expand their sound by adding live instruments - MCA was one helluva bass player -- and successfully weave rock, funk, jazz and punk influences into their later albums. Yauch's friend and peers took to Twitter immediately to express their love and sadness for this recently inducted member of the Rock and Roll Hall of Fame: