Photo Afeni Shakur, a civil rights activist and former Black Panther whose tumultuous but close relationship with her son, the rapper Tupac Shakur, was the inspiration for much of his work, died on Monday in California.

Ms. Shakur was pronounced dead around 10:30 p.m., about an hour after deputies responded to reports of a cardiac arrest at her home in Sausalito and took her to a hospital, the sheriff’s office said on Twitter.

Ms. Shakur had been the driving force behind an effort to continue the legacy of her son, who died at 25 in a drive-by shooting in Las Vegas in 1996.

She established the Tupac Amaru Shakur Foundation in 1997, and shepherded the release of new material through his estate.

Last year, snippets of Mr. Shakur’s voice were used in a Powerade commercial and on a track from Kendrick Lamar’s album “To Pimp a Butterfly.” In 2012, a “Tupac hologram,” was unveiled at the Coachella music festival in California to much fanfare.

A biopic on Mr. Shakur, “All Eyez on Me,” is also in the works.

Ms. Shakur was born Alice Faye Williams in Lumberton, N.C., and moved to New York with her family in the 1960s, later changing her name and advocating for social change.

In the song “Dear Mama,” Mr. Shakur rapped about his mother’s drug addiction and her efforts to raise him as a single mother, portraying their bond as ultimately rooted in respect and honesty.

Afeni Shakur