Phosphorylation cascades are similar to a row of dominoes falling down, instead of one domino knocking down the next, a phosphate being added activates the message. In this way, a series of different are each one after another. Inactive protein kinase 1 gets a added and now it is protein kinase 1. Active protein kinase 1 transfers a and now inactive protein kinase 2 is now . This continues until the desired is activated to cause a cellular response.