To monitor the formation of liquid-like droplets in protein solutions containing different concentrations of monomers, turbidity of absorbance at 600 nm was applied as an indicator. TLC-M absorbance was negligible at 600 nm. The relative turbidity is defined as ln(T/T0), where T and T0 are the light transmittance with and without sample, respectively (2). Protein solutions were added into cuvette and measured on Spectramax M5 (Molecular Devices) at different time intervals. Data are presented in Fig. 2D and figs. S3A and S4C.