1. * Wnt proteins bind to frizzled receptors and inhibit the degradation of b-catenin

2. Extracellular signal molecule
Receptor protein
Intracellular signaling proteins
Target proteins
這樣一個機制包括細胞外的signal molecules, 細胞內的signaling proteins, 以及target proteins
Metabolic enzyme
Gene regulatory protein
Cytoskeletal protein

3. Extracelluar signal molecules bind to specific receptors

4. Three classes of cell-surface receptors

5. Gene transcription is activated by a rise in cAMP conc
Amplifier and transducer protein
Relay protein
Messenger protein

6. MAP-kinase serine/threonine phosphorylation pathway activated by Ras
Raf
MEK
MAPK

7. Cytokine receptors activate the Jak-STAT signaling pathway
Tyk2
Signal transducers and activators of transcription

8. * Wnt proteins bind to frizzled receptors and inhibit the degradation of b-catenin