Protein sample preparation for solid-state NMR investigations

•Sample preparation is central in solid-state NMR in order to analyze proteins.•New solid-state NMR methods allow to address large and complex (membrane) proteins samples.•Selective labeling techniques become central to resolve the resonances.•Smaller and smaller amounts of protein are needed with faster magic-angle spinning.•In this context, cell-free expression becomes a promising tool for sample preparation.