A substance directly involved in cellular communication

within the human body is

(1) an antibody (3) a hormone

(2) an antibiotic (4) a starch

Hormone is a substance that directly involve in cellular communication within the human body.

Explanation:

A hormone is a restrictive substance created in an organism and transported in tissue fluids like blood or sap to stimulate specific cells or tissues into action.

It is a synthetic substance with result thereto of an animal or growth regulator.

It is a person's sex hormones as control to influence behavior or mood.

Hormone is a substance that directly involve in cellular communication within the human body.