OK....but what are those pathways that follow...not so briefly. My question was perhaps
oversimplistic to the point that you defined the major ligand as MHC class II and stop at
that. Please define "signal transduction pathways". For example, is there interaction with
other CD4 co-ligands (intra- or extra- cellular) which modulate the response to a ClassII
MHC/peptide complex, depending on the nature of the peptide in the complex (self, viral,
oncogenic, etc.)...or is CD4 just a "clamp" to hold the MHCII/peptide to the TCR?
The CD4 can't be upstream of a lytic or cytotoxic pathway directly if it's also on APCs, can
it?
So, again... *specifically* what does it do?
