DNA repair protein AlkB with DNA. Molecular model of the DNA (deoxyribonucleic acid) repair protein AlkB (purple) bound to a strand of double-stranded DNA (ds-DNA, red and green). AlkB is the bacterial (Escherichia coli) equivalent of similar repair proteins in humans. These repair proteins reverse methylation damage such as that related to 1-methyladenine (1-meA). This DNA methylation process is critical to genetic changes, and defects in the process are thought to cause conditions such as cancer, as well as affect genomic imprinting and X-chromosome inactivation.