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Valerie Bertinelli is mourning the loss of her TV mom, Bonnie Franklin, who passed away on Friday at age 69 following a battle with pancreatic cancer. Franklin is most well-known for her role as Ann Romano on sitcom "One Day at a Time" -- a single mom to teenaged daughters Barbara (Bertinelli) and Julie (Mackenzie Phillips) in a high-rise apartment building tended to by a helpful superintendent, Schneider (Pat Harrington, Jr.).

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"My heart is breaking," Bertinelli, 52, wrote in an emotional tribute on her website. She and Franklin reunited onscreen back in 2011 when Franklin guest-starred on Hot in Cleveland. "Bonnie has always been one of the most important women in my life and was a second mother to me," continued Bertinelli, who became a teen star on the CBS sitcom, which ran from 1975 to 1984.

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Continued the actress: "The years on 'One Day At A Time' were some of the happiest of my life, and along with Pat and Mackenzie we were a family in every way."

The late Emmy and Golden Globe nominated actress -- also a respected theater performer -- is survived by her mother, Claire Franklin, and stepchildren Jed and Julie Minoff.

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"She taught me how to navigate this business and life itself with grace and humor, and to always be true to yourself," Bertinelli writes. "I will miss her terribly. "