Illustration of the US biologist H Robert Horvitz (born 1947). Horvitz is best known for his work on programmed cell death, or apoptosis, which he studied in the nematode worm Caenorhabditis elegans. Apoptosis is a highly regulated process that is vital for foetal and organ development and to remove damaged or diseased cells. In 1986 Horvitz discovered two genes, ced-3 and ced-4, which were the first shown to be required for apoptosis to occur. He later identified the ced-3 equivalent in humans and another gene, ced-9, that protected cells against apoptosis. Horvitz was awarded a share of the 2002 Nobel Prize in Physiology or Medicine for this work along with Sydney Brenner and John Sulston.