What is crosstalk in cellular signaling pathways, and how do insulin and epinephrine pathways demonstrate this phenomenon?

In the treatment of asthma, how do cyclic AMP and cyclic GMP differ in their effects on smooth muscle contraction?

What is the physiological impact of phosphodiesterase inhibitors on cyclic GMP levels?

What is the effect of Viagra on cyclic GMP levels and smooth muscle contraction in erectile function?

What is the primary function of integrin adhesion receptors in cellular structure?

What is the role of nitric oxide as a signaling molecule, and how is it synthesized?

How do steroid hormone receptors influence gene expression as transcription factors?