Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

they amplify the original signal manyfold.

Explanation:

A phosphorylation cascade can be described or is regarded as a sequence of events, where one enzyme phosphorylates another, causing a chain reaction, leading to the phosphorylation of thousands of other proteins.

Phosphorylation cascades is considered to be important because it plays a vital role in regulating many intra cellular processes such as growth, proliferation and cell division.

In conclusion, it should be understood that, cells make use of phosphoylation cascades for signal transduction, bringing outside stimuli to the interior of the cell, to stimulate a response.