Illustration of the Swedish biochemist Tomas Lindahl (born 1938). Lindahl is best known for his work on DNA (deoxyribonucleic acid) repair and the genetics of cancer. He discovered base excision repair, the mechanism by which small spontaneous DNA damage within a cell is repaired. Defects in this repair pathway can lead to malignant (cancerous) transformation of a cell. Lindahl received a share of the 2015 Nobel Prize in Chemistry, along with Aziz Sancar and Paul Modrich, for their work on DNA repair mechanisms.