Just one day after announcing that her mother had sadly passed away, Katie Couric is leading a pack of Hollywood stars in a "Stand Up To Cancer" telethon.

"My heart is broken. I lost my mom and best friend. We love you and miss you, Mom/Granny," Couric tweeted on Friday. She added, "my world and the world at large seems terribly off."

The TV host also posted a picture of her 91-year-old mother, Elinor H. Couric, on Facebook, captioning it, "She loved fiercely and was fiercely loved."  

Couric did not let the family tragedy keep her from serving as host of the Stand Up To Cancer telecast, however.

The program, which is being broadcast live on ABC, CBS, FOX, and NBC will feature performances and appearances from a variety of stars who are pledging themselves to supporting cancer research. 

The celebrities gathered at the Dolby Theatre in Los Angeles for the "Stand Up To Cancer" event.  

According to E! News, "James Bond" star Pierce Brosnan shared his experience losing his first wife Cassandra, as well as daughter Charlotte, to ovarian cancer. "To watch someone you love have his or her life eaten away bit by bit by this insidious disease, that part of your sorrow becomes an indelible part of your psyche. I held the generous, strong, beautiful hand of my first wife Cassie as ovarian cancer took her life much too soon. Just last year, I held the hand of my funny, wonderful daughter Charlotte before she, too, died from this wretched inherited disease," he shared.

Mike Myers attempted to add a little humor to the night by saying, "Canada invented insulin in treatment of diabetes, was a pioneer of radiation technology in the treatment of cancer and while Canada did not invent the degenerate drug-loving mayor, the city of Toronto just may have perfected it. Thanks Rob Ford!"

Katie Couric Leads A-List "Stand Up To Cancer" Telethon, TV Host Appears Just One Day After Announcing Mother's Death 

Couric filled her Twitter page with updates on the telecast, imploring fans, "Tonight, some of the biggest stars in Hollywood are coming to the ‪@SU2C event and they could be calling you!"