Pop singer Katy Perry is mourning the death of the music executive who helped to launch her career.

Angelica “Geli” Cob-Baehler, a music executive, 47, who was instrumental in the early stages of Perry's career, recently lost her battle with cancer.

Perry took to Instagram to share several pictures of the two of them together. She wrote:

"Six days ago, one of my biggest champions and realest friends, Angelica Cob-Baehler moved on from this place. She was one of the strongest women I have ever known - fighting her cancer like friggin’ Rocky, enduring chemo, immunotherapy, a tracheotomy, feeding tubes for months on end, and experimental cancer treatment trials. I watched her go through many stages for over a year, but a few things remained constant: her sarcastic/wicked sense of humor, her positive outlook, and the incredible love she had for her family."

She continued: "We had a lot of wins together for over 10 years, and I am incredibly grateful she was a born fighter/no shit-taker because she practically willed me into existence as a young artist when she “stole my files” from limbo at Columbia Records and brought them to life at Capitol Records. She was like a big sister to me, showing me the ropes and always having my back. She never became a yes-person and was quick to check me when I needed checking - that was family. I have procrastinated posting this because it makes it feel a little too final, but I don’t believe people ever really die - she just had to leave that body behind. Out of body, and full of spirit now.

"Sadly, she also left behind two amazing young girls, and an incredible husband who was the definition of ROCK through this whole process. As for me, I’ll never let them forget that Angelica embodied the angel in her name, was a woman of incredible integrity and character, a massive giver, and a DOPE human being. I know today is #GivingTuesday, and if you have been a longtime KatyCat and a friend of mine or Geli’s, let’s honor her by donating to her favorite charity, Generosity.org by clicking the link in bio. She may be gone from this place, but she will never be forgotten. Rest in power, my angel, and don’t worry, we got Chapman and the girls. #RIPGeli"

Perry and Cob-Baehler have been friends for over a decade.