Explain the difference between the actions of water-soluble and lipid-soluble hormones.  Your explanation should include a detailed description of how/where these two different classes of hormones bind to receptors and what each type of mechanism triggers.  Specifically, detail the events involving water-soluble hormones with G-protein coupled receptors and the events that occur when a lipid-soluble hormone binds to an intracellular receptor, triggering transcription and translation.  Include two simple, numbered, labeled diagrams to help in your explanation.

What distinguishes a steroid receptor from a receptor tyrosine kinase receptor or a G-protein-coupled receptor?

Figure 9.8 HER2 is a receptor tyrosine kinase. In 30 percent of human breast cancers, HER2 is permanently activated, resulting in unregulated cell division. Lapatinib, a drug used to treat breast cancer, inhibits HER2 receptor tyrosine kinase autophosphorylation (the process by which the receptor adds phosphates onto itself), thus reducing tumor growth by 50 percent. Besides autophosphorylation, which of the following steps would be inhibited by Lapatinib? Signaling molecule binding, dimerization, and the downstream cellular response. Dimerization, and the downstream cellular response. The downstream cellular response. Phosphatase activity, dimerization, and the downsteam cellular response.

Second-messenger systems ultimately bring about the desired cell response by inducing a change in the shape and function of particular designated intracellular proteins. (True or false?)