STOCKHOLM (AP) — Two scientists won the Nobel Prize in physiology or medicine on Monday for their discovery of microRNA, tiny bits of genetic material that serve as on and off switches inside cells that help control what the cells do and when they do it.

If scientists can better understand how they work and how to manipulate them, it could one day lead to powerful treatments for diseases like cancer.

The work by Americans Victor Ambros and Gary Ruvkun is “proving to be fundamentally important for how organisms develop and function,” according to a panel that awarded the prize in Stockholm.

Ambros and Ruvkun were initially interested in genes that control the timing of different genetic developments, ensuring that cell types develop at the right time.

Their discovery ultimately “revealed a new dimension to gene regulation, essential for all complex life-forms,” the panel said.