Conversation so far:
How was Henrietta Lack involved in medical research?
Henrietta Lacks' cancer cells are the source of the HeLa cell line, the first immortalized human cell line and one of the most important cell lines in medical research.
Who did the research on Henrietta Lacks' cells?
George Otto Gey was the first researcher to study Henrietta Lacks's cancerous cells.

Question: What did Get discover about her cells?
Self-contained rewrite: What did Georgo Otto Gey discover about Henrietta Lacks' cells?