A protein that has two “personalities” may be the key to curing cancer, according to a new study led by Oxford University researchers.

The “Jekyll-and-Hyde” protein, known as E2F, can both promote and hinder tumor cell growth – and British researchers believe they found a way to control the unusual protein into remaining the deadly “Mr. Jekyll” and kill cancer cells.

“This mechanism for switching a key protein is very novel. Nothing else I've come across behaves like it,” Professor Nick La Thangue of the Department of Oncology at Oxford University, said in a statement. “Subtle changes in terms of the chemistry of the protein have dramatic and polar opposite effects on the tumor cell, either allowing them to continuously grow or switching them to cell death mode.”

The study, published in the journal Molecular Cell, is the first to explain how the dual nature of the “Jekyll-and-Hyde” protein works.

Researchers showed how the E2F protein determines the fate of a cell. Depending on the position where two enzymes land on the protein, it can either act as Dr Jekyll, which leads to cell death. Or, it can become Mr. Hyde and promote cell growth.

“It's like there's an angel and a devil competing to get on each shoulder of the protein. Which one gets the upper hand is able to whisper in the ear of the protein and tell it what it should do,” La Thangue said.

Armed with this newfound knowledge, La Thangue says the next goal is to create cancer drugs that imitate this behavior. “With the molecular flag on one shoulder, E2F goes into cell kill mode. With the flag on the other, it goes into cell growth mode. The challenge is to mimic this process with drugs, and reinstate the death pathway in tumor cells,” he said.

While the protein was first discovered in 1990, La Thangue is confident his team’s findings will help develop new chemotherapy treatment.

“We have a program aimed at developing small molecule drugs that target this enzyme,” La Thangue told Fox News. “While it’s not coming out tomorrow, at the same time, it’s not 10 years away. I’d say we’re a few years away until we move to clinical trial.”