Somewhere between 30% and 50% of all drugs on the market target a G protein-coupled receptor. For each agent,

-          Write an in-depth description of the agent and its mechanism of action.

-          Are they agonists or antagonists?

-          What GPCR or GPCRs do they bind?

-          What is the endogenous ligand? Include in your descriptions the sources of the agents.

-          Were they isolated from nature, stumbled upon randomly, or intentionally synthesized?

-          When and by whom? If one of the agents is a "dirty drug," be sure to mention other sites of action besides the GPCRs.

-          If you can find the information, what signal transduction pathway is activated or inhibited by each drug?

-          What are the applications of your agents? Are they only used in research or does either have a clinical use?

Pharmacological agent and target

staurosporine and protein kinases

Signal transduction pathways represent a wealth of potential targets for pharmacological intervention.

-          Write an in-depth description of agent (staurosporine and protein kinases) and its mechanism of action. Include in your description the source of the agent.

-          Was it isolated from nature, stumbled upon randomly, or intentionally synthesized?

-          When and by whom?

-          If the agent is a "dirty drug," be sure to mention other sites of action.

-          What are the applications of the agent?

-          Is it only used in research or does it have a clinical use?

Be sure to cite all of your references.

NO DIRECT QUOTES! Write a single, cohesive response.