CGK733 was a synthetic chemical substance which was reported in 2006 to have remarkable properties in reversing cell senescence (aging). However, the entire work behind the discovery of this compound has since been found to be falsified and the authors of the original reports have retracted all their claims. CGK733 was claimed to be an inhibitor of ATM/ATR kinases, which are involved in DNA damage repair. CGK was claimed to extend the lifetime of cultured cells by approximately 20 divisions, or roughly 25%, specifically in mammalian cells.