eLife Assessment
This is an important study describing 'SPEx', a broadly accessible method that combines cell expansion, laser microdissection, and mass spectrometry to enable subcellular proteomic profiling. The authors provide convincing evidence that this flexible integration of established techniques provides a robust and practical approach for compartment-resolved spatial proteomics. The authors support their main claims with appropriate validation across multiple subcellular compartments and show that the method can recover known markers while also identifying previously uncharacterized components. Overall, the work is likely to be of broad interest to cell and molecular biologists, particularly those seeking scalable and cost-effective strategies for mapping organelle composition.