A. The graph should have SD not SEM, ideally it should be presented as a "beeswarm graph" to visualize the variability - is the difference attributable to a small proportion of very large endosomes in PEI-treated cells, or are all endosomes slightly enlarged. One cannot distinguish between these possibilities by this graph. Also, do all endosomes contain PEI? If not, are the ones that do contain PEI significantly larger than the ones that do not? Is there evidence of endosomal rupture on any images? Are there "free-floating" PEI particles outside of endosomes, which would be predicted from the "rupture" hypothesis? All these are relatively simple questions that could be addressed using already collected data.
B. Use "untransfected" or "control" instead of WT - WT implies that there were mutants involved. What happened to the error bars in the control (black bars)?
C. Should the total Galectin fluorescence change in response to lysosomal rupture? I would expect the total fluorescence to stay the same and instead the number/size of puncta to change? How is it possible that relocation of the protein changes the total fluorescence/surface area? The results section talks about the size and number of punctae, but this is not shown in the graph.