response to 2-O-acetyl-1-O-hexadecyl-sn-glycero-3-phosphocholine +
response to 4-nitroquinoline N-oxide +
response to 5-fluoro-2'-deoxyuridine
response to acadesine +
response to acetaldehyde +
response to acetate +
response to acetylcholine +
response to acetylsalicylate
response to acrylamide +
response to alcohol +
response to amino acid +
response to amylopectin +
response to antimycin A +
response to arsenite ion +
response to ATP +
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an ATP (adenosine 5'-triphosphate) stimulus.