In the case of the phosphoric cascade, we saw that the IP three has to bind onto a specific ligand gated calcium on channel on the Er membrane to actually allow the movement of the calcium from the Er lumen and into the cytoplasm. And only then can protein kinase C and the calmodulatenant protein kinase actually be activated. Now, in the case of insulin signaling, we said that the IRS one must bind onto that insulin receptor to actually act as an adaptive protein to allow the attachment of the phosphor nosetie three kinase, that specific type of lipid kinase that is needed to actually transform the pip two into the pip three molecule that we mentioned right over here. And finally, in the EGF signaling pathway, we said that the GRB two must be able to bind and attach onto that EGF receptor to actually act as the adaptive protein and allow the attachment of the SOS. And only then can the SOS actually activate that Rasp protein which goes on to activate raft, which then goes on to activate the mex and the IRCS and so forth. So interactions play very important roles in these signal transduction pathways.