The family of Henrietta Lacks -- a Black woman whose cells, harvested without her knowledge, were used for several medical breakthroughs -- announced plans Thursday to sue the big pharmaceutical giants that profited from those discoveries.

In 1951, the 31-year-old Lacks, a mother of five, died of cervical cancer at Johns Hopkins Hospital in Baltimore.

During attempts to treat her, cells from her tumor had been taken and transmitted to a researcher without her knowledge -- and used for decades without her family's knowledge.

"For far too long, the Lacks family has been exploited, the Lacks family has been taken advantage of. And we say no, no longer. No more," her grandson Alfred Carter said.

"So pharmaceutical companies: you are on notice."

The Lacks family has retained prominent civil rights attorney Ben Crump, who has represented the relatives of many African Americans killed in incidents with police, including the loved ones of George Floyd.

"Black life must be valued in America," Crump said, announcing he would file a complaint on October 4 to mark the 70th anniversary of the disputed samples.

A portrait of Henrietta Lacks, known for her unusually fast cell growth, on show in New York April 6, 2017
A portrait of Henrietta Lacks, known for her unusually fast cell growth, on show in New York April 6, 2017 GETTY IMAGES NORTH AMERICA / Nicholas Hunt

Lacks' cells, dubbed HeLa cells, have enabled laboratories around the world to develop vaccines -- especially against polio -- as well as cancer treatments and certain cloning techniques, an industry worth billions of dollars.

Her family first discovered how Lacks had helped medical science in the 1970s, and only understood her legacy thanks to Rebecca Skloot, who wrote the 2010 best-seller "The Immortal Life of Henrietta Lacks."

"They treated her like a specimen, like a lab rat," her granddaughter Kimberly Lacks said.

Crump's colleague Christopher Seeger said the complaint would target any company that had "profited from the use" of the cells and had not reached an agreement to compensate the family.

Neither Crump nor Seeger named specific companies expected to figure in the legal action.

In 2013, Lacks' descendants did reach a deal with Johns Hopkins University for two family members to sit on a committee responsible for authorizing future uses of HeLa cells. But the agreement did not include compensation.

Johns Hopkins Hospital says that it has never sold or benefited from the discovery or distribution of HeLa cells, and does not own the rights to them.