In the UK, political debate over stem cells continues to focus on whether scientists should be allowed to create hybrid humananimal embryos. This futuristic research may eventually lead to rewarding discoveries about incur-able diseases - and emotive arguments by some religious groups trying to ban it should be resisted. At the same time, some scientists and patient advocates have been unable to resist hyping hybrid embryo research, by implying that it could produce cures in the near future. Sir Martin Evans, the stem cell pioneer and Nobel prizewinner, acknowledged that this week.

In the US, meanwhile, the Food and Drug Administration is preparing for the much more immediate business of actually regulating the world's first clinical trials of pro-ducts based on human embryonic stem cells. The FDA held two days of hearings this week to draw up guidelines for assessing the risks and benefits of stem cells in the clinic. Later this year, the agency expects to receive applications to test such treatments on patients; the pioneer is likely to be Geron, a Californian company aiming to restore limb movement in people paralysed by spinal injury.