What are the steps of cell signaling?

The three main steps of cell signaling are: reception, transduction, and response in that order respectively. 

1. Reception: A cell detects a signaling molecule from the outside of the cell. Membrane receptors play a vital role in cellular communication by binding to specific signaling molecules, or ligands. This binding event leads to the production of a second signal, known as a second messenger, within the cell. The second messenger functions to transmit the signal from the membrane receptor to the intracellular environment by altering the shape or merging with another protein.
2. Signal transduction pathway: Signaling molecules bind to receptor proteins and cause the receptor protein to alter its shape. This alteration starts the process of transduction. Signal transduction is a pathway involving many steps, where each step changes the next molecule in the pathway.
3. Response: Signaling finally triggers a specific cellular response such as the regulation of one or more cellular activities.