Match the following signaling pathways/receptors with their activation mechanisms or proteins. A. Activate components by removal of a peptide piece. B. Degradation of an inhibitor through its phosphorylation C. G-protein activation of a series of kinases D. Activation of downstream components through binding of second messenger molecules such as CAMP. E. Requires a protease and is used in contact dependent signaling F. Activation through direct phosphorylation of transcription factors by the receptor (thereby exposing their active binding sites).