(LOS ANGELES) -- For seven seasons, The Mary Tyler Moore Show brightened viewers' lives.
Mary Richards, the title character played by Mary Tyler Moore, along with her pals Rhoda Morgenstern (Valerie Harper), Phyllis Lindstrom (Cloris Leachman), Sue Ann Nivens (Betty White) and Georgette Franklin (Georgia Engel) made America laugh from 1970 to 1977.
Now, four decades after the program ended, the ladies of the show are back together again on an episode of the TV Land sitcom Hot in Cleveland, which co-stars White.
ABC News' Katie Couric caught up with Moore, Harper and White on the set of White's new show, and she asked them what it was like to work together after such a long time.
White replied that it was "heaven."
The Mary Tyler Moore Show, which revolved around the exploits of the independent career woman played by Moore, had a significant impact on television in the 1970s. During its run, the show earned 29 Primetime Emmy Awards, making it one of the most successful TV shows of all time.
The actresses say they don't take the show's legacy for granted, and they cherish their friendship, especially after Harper's recent diagnosis of terminal brain cancer.
Harper, 74, has said her body is responding better than expected to her treatment, and based on recent tests and scans, the cancer may be retreating for now, according to a report last week in People magazine.
She told Couric that she doesn't have "a lot of symptoms."
Harper had originally been given three to six months to live when she was diagnosed in January.
"I'm not a believer in the good old days," Harper added. "This, right now, is the best day. Why? Because here we are."
She added that having her friends around filled her heart "with so much happiness."
The ladies' reunion episode of Hot in Cleveland airs this month.
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