1. General idea and concepts of cell-cell signaling
Cell signaling: Mechanisms that one cell uses to communicate with and influence the behavior of another cell. In a broader sense, the signaling could include environmental cues received by a cell such as smell, light, mechanic pressure, and heat etc.
Three ways of cell signaling
long-ranch signaling by secreted molecules
contact signaling by plasma-membrane-bound molecules
contact signaling via GAP junctions

2. Receptors:
a. Enzymed-linked receptors
-receptor protein kinases: tyrosine kinases, serine/thronine kinases
- receptors coupled to protein kinases
-protein tyrosine phosphatase receptors
-ligand binding leads to activation of intrinsic enzyme activity, such as guanylyl cyclase catalytic domain
b. G protein-linked seven transmembrane receptors
c. Ion channel-linked receptors
d. Intracellular Receptors--Steriod hormone receptors
e. Receptors with death domain

3. Signal transduction pathways Wnt signaling pathway
TGF beta signaling pathway
Notch signaling pathway
Small RNA signaling pathways
cell death pathways
- genetic pathways
- biochemical pathways
- death signaling pathways
- radiation-induced bystander effect pathway
- engulfment signaling pathways

4. Embryo development
Mosaic Development (autonomous specification: determined by local determinants and no cell-cell interaction)
Experimental test: remove one blastomere, the blastomere still develop as it will be in the original embryo
Regulative Development (conditional specificaiton: determined by cell-cell interaction and local determinants not important; e.g. mouse)
Experimental test: if remove one blastomere, the other blastomere will take over and the embryo is fine.
Intermediate (Xenopus, fly and C. elegans)

5. Experimental systems
C. elegans
Drosophila
Mouse
Human cultured cells

6. Approaches and techniques Genetic approaches
Genetic approaches
Suppressor screen
Enhancer screen
Phenotypic screen
Epistasis analyis
Complementation tests
Mosaic analysis
Transformation rescue
Sequencing of mutations
Maternal effects

7. Biochemical approaches
Co-IP
hard-core protein purification
mass spectrometry analysis
Western blot analysis
Enzymatic assays (kinases, proteases)
Pulse chase experiments
Molecular Biological approaches
Over-expression
In vitro mutagenesis on DNA
dsRNA injection
Cell Biological approaches
Cell or tissue isolation, mixing, and transplantation
Micro-manipulation
Immunostaining
GFP fusion labeling
LacZ staining
Electron microscopy (EM) and tomography

8. Advantage or disadvantage of various approaches
Genetic approach
Help systematically identify the important components in a particular biological process
Help determine the genetic relationships among different genes in the same pathway.
But genetics often can not reveal the mechanisms underlying the biological process.
Biochemical approaches
Very effective in elucidating the detailed mechanisms underlying a biological process.
Can also help identify components of a biological process but usually can not reveal the whole picture and is restricted by the availability and relative quantity of materials, the experimental techniques or methods.

9. Good luck!
Keep reading and thinking