Dic: act on

• A patient will usually listen to the doctor's advice and act on it.
• He's taking a dangerous drug: it acts very fast on the central nervous system.

VERB | If you act on advice or information, you do what has been advised or suggested. | to regulate one's behaviour in accordance with (advice, information, etc.)

VERB | If a force or substance acts on someone or something, it has a certain effect on them. | to have an effect on (illness, a part of the body, etc.)

.... Cobuild, Collins

CF. act (up)on something

• I will act on this immediately.
• The police refused to act upon his complaint because he was an ex-convict.
• Ken has never acted on the stage or in front of a camera.

1. to take action on a particular problem. (Upon is more formal and less commonly used than on.)
2. to take action because of some special information.
3. to perform on something, usually the stage (in a theater).

.... McGraw-Hill Dictionary of American Idioms and Phrasal Verbs,
http://idioms.thefreedictionary.com/act+on