The ATM (Ataxia-telangiectasia mutated) protein belongs to a serine/threonine protein kinase, which contains 3056 amino acid residues and belongs to the phosphatidylinositol 3-kinase (PI3K) family. ATM signaling pathway is a more complex process that includes three stages including DNA damage recognition, signal transduction, effects, and more. When eukaryotic cells experience DNA double-stranded damage caused by ionization or UV radiation, they first step is to identify the break point, and then the ATM protein dimer molecules are autophosphorylated and separated into active ATM protein monomers. The monomers induce a series of complex phosphorylation cascades in downstream corresponding substrates. The process eventually causes cell cycles such as G1/S, S, or G2/M arrests, DNA repair or apoptosis, preventing errant genetic information from being delivered to progenies and maintain chromosomal stability and prevent cancer.