They showed that adult cells could be reprogrammed to become cells with the properties of an embryonic stem cells

Kathrin Plath and William Lowry

Explanation:

Kathrin Plath and William Lowry and researchers at the University of California in Los Angeles(UCLA) were able to reprogram adult cells to become develop properties of embryonic stem cells which are very important as they can become any type of cell in the body which can have very important implications in medicine.

They did this by genetically altering the cells to enable them age backwards to a point where they were like the aforementioned stem cells.