Which of the Following Substances Activates Protein Kinases and Thus

Question

Which of the following substances activates protein kinases and thus acts as a second messenger?
A) insulin
B) ACTH
C) epinephrine
D) cyclic AMP
E) TSH

Accepted Answer

Cyclic AMP is a common second messenger that activates protein kinases, leading to various cellular responses. Insulin, ACTH, epinephrine, and TSH can activate other signaling pathways but do not directly activate protein kinases as a second messenger.