Al3+promotes the formation of SDS stable tau oligomers more efficiently after tau phosphorylation. A. Cross-correlation amplitudes (G (0)) show mild proaggregatory activity of the organic solvent DMSO, which was significantly higher for mTau. Al3+ promotes intense protein oligomerization. Measurements were taken from 15 independent samples; each sample was measured four times. B. 2D histograms of detected photons indicate the formation of smaller oligomers in presence of DMSO (mean 76 monomers per oligomer for mTau, 26 monomers for pTau) compared to Al3+ (mean 220 to 240 monomers per oligomer). C. Cross correlation amplitude immediately before (T0) and 100 min after (T100) addition of SDS to the aggregation assay. Significant reductions of aggregation levels at T100 are indicated by the symbols over the error bars, while significant differences between pTau and mTau are indicated by the symbols over the wide bars. Measurements were taken from 7 independent samples. D. Cross correlation amplitude at T100 normalized against T0 shows increased SDS-resistance of Al3+ induced oligomers compared to DMSO. Levels of significance are displayed as * = p < 0.05; ** = p < 0.01; ‡ = p < 0.001.