Disclaimers
Lacking reference ligand: A sufficiently balanced ligand may not yet exist for all investigated receptors and pathways. In these cases, bias can still be measured but should not be considered an assessment of pathway-bias but rather a benchmark relative to a given, general reference ligand (see preceding section). When no balanced ligand is available, one can show a bias plot for each tested ligand.
Context specific bias: Many researchers argue, rightly so, that a ligand referred to as balanced will not be balanced in another system or assay. Therefore, any claim of a ligand being balanced and tested ligands exhibiting pathway-bias is always system specific (which is also true for all biased ligand/signaling studies).