SANTA CLARA, California (Ticker) -- The San Francisco 49ers today lost one of the cornerstones of their coaching staff.

Bobb McKittrick, the 49ers' offensive line coach for the past 21 seasons, lost a long battle with cancer. He was 64.

McKittrick had undergone several surgical procedures and chemotherapy treatments since being diagnosed with the disease in January 1999.

He joined the San Francisco staff in 1979 and is one of only two coaches who were members of all five of the Niners' Super Bowl championship teams. He spent 28 years as an NFL assistant, including stints with the Los Angeles Rams (1971-72) and San Diego Chargers (1974-78) before helping build the line that protected Hall of Fame quarterback Joe Montana and two-time Most Valuable Player Steve Young.

"Bobb McKittrick has been universally acclaimed as one of the great coaches of our time," said 49ers general manager Bill Walsh, who had McKittrick on his staff for three Super Bowl titles. "He was the most successful offensive line coach the game has ever seen. His spirit and standard of excellence will always be a part of the 49ers tradition. He was a great man and will truly be missed by all of us."

McKittrick developed the likes of perennial Pro Bowlers Jesse Sapolu, Harris Barton, Guy McIntyre and Randy Cross.

Born in Baker, Oregon, McKittrick graduated from Oregon State in 1958 and coached at his alma mater from 1961-64 before joining the staff at UCLA, where he spent five years before turning his attention to the professional ranks.