Mutagenesis is the process of changing genetic information. This may occur spontaneously or from exposure to mutagens. The mutations that arise may be beneficial or harmful to the organism; a new trait may appear, but the mutation may also result in impaired gene function or death. In the laboratory, mutagenesis can help to determine gene function. Researchers can introduce specific mutations by using DNA intercalators and crosslinkers. DNA intercalators are molecules capable of fitting between nucleic acid base pairs. This reversible action leads researchers to new drugs and treatments since it can, for example, inhibit DNA replication in rapidly growing cancer cells. Crosslinking is when some agent connects two different positions either on the same strand or opposite strands of DNA. This cross-linking prevents DNA replication, leading to possible cell death and anticancer action. Several DNA intercalators and crosslinkers are available at Sigma-Aldrich for nucleic acid research.