<prompt> Which of the following has cyclic GMP as a second messenger ?Growth hormoneFSHInsulinThyroxin  <response>: Insulin action in ceain tissues are mediated through CGMP which activates protein kinase. Cyclic GMP is synthesized from the nucleotide GTP using the enzyme guanylyl cyclase. Cyclic GMP also serves as the second messenger for the following Atrial natriuretic peptide ANP Nitric oxide NO The response of the rods of the retina to light. Some of the effects of cGMP are mediated through Protein Kinase G PKG. 