How biologist reached his 'eureka' moment

From the start of his career as a biologist, Sir Paul Nurse was convinced that understanding how cells divided and grew was the key to knowing what went wrong in cancer, when cells multiply in an uncontrolled, malignant fashion.

He started by studying yeast cells on the assumption that all living organisms shared the same basic mechanism of cell division. Yeast cells are much simpler than human cells, but most medical researchers thought this an eccentric approach and took little notice of his work.

His team made its first breakthrough in the early 1980s, with the discovery of the gene that regulated cell division in yeast, which they called cdc2. They also identified three different proteins that control the speed and timing of cell division.

At about the same time, Dr Lee Hartwell, the American joint winner of the prize, was working on cell division in yeast and frogs, and made significant advances in understanding the mechanism.

Then in 1987, Sir Paul's team made the discovery that secured its reputation. They showed that the same gene, cdc2, which they had identified in yeast cells, was present in human cells.

They had found a universal key to cell division that underlay the mechanism in all living things from yeast, to frogs, to humans. "It meant everything ... was controlled in the same way. That was a eureka moment," Sir Paul said.

Meanwhile, Dr Timothy Hunt was working on a different aspect of cellular function when he discovered cyclins – the proteins that regulate the process of cell division. Ten cyclins have now been identified. The contribution of the three men has added up to one of the most significant advances in the understanding of cancer in recent decades.

Sir Paul's work laid bare the working of the engine of cell division, while Dr Hunt's contribution was to understand the mechanism of the gearbox that controlled the speed of growth. Dr Hartwell's work, meanwhile, uncovered a class of genes that oversaw the cell cycle.

In its citation, the Karolinska Institute in Stockholm said yesterday that the findings were about to be "applied to tumour diagnostics ... and may in the long term also open new principles for cancer therapy". The winners were selected from nominations received from professors, past Nobel prize laureates and other specialists from around the world.

The final choice was made in a vote yesterday by the 50 professors at the Karolinska Institute who make up the Nobel Assembly.

The Nobel prizes are traditionally handed out on 10 December, the anniversary of Alfred Nobel's birth. For this centennial year, all living laureates have been invited to the ceremonies and related seminars, with about 150 expected in Stockholm and 30 in Oslo, including the former South African president Nelson Mandela and the former Soviet leader Mikhail Gorbachev.