bioactive molecules ONLY active via microinjection?

[mark]

Kate Michie wrote:
> 
> I am looking for compounds that CANNOT enter cells by themselves (ie they
> are too large, or are not endocytosed). I want these compounds to use as a
> cargo to test various drug delivery methods to see if I CAN get them into
> cells.  I am trying to find a cargo that would be detectable once it gets
> into the cell, ie. an indication that it has been sucessfully delivered.
> Does anyone know of anything that fits this description?
> Thanks for any ideas.

Why don't you call or look up papers from the liposome corporation?