Validation of candidate compound efficacy for tau reductions in M17 neuroblastoma cells by standard Western blot. M17 neuroblastoma cells were treated at 90% confluency for 24 hours with respective μM concentrations of drugs shown at the top of each lane. Cells were then harvested and homogenized, normalized for protein concentration and subjected to SDS-PAGE followed by probing for total tau and GAPDH. All 5 compounds altered tau levels. Several compounds caused fragmentation of tau relative to vehicle treated cells. Note the high molecular weight species present at the 1 μM dose of daunorubicin and the 1 and 0.1 μM doses of camptothecine, perhaps indicating the formation of a multimeric structure during tau degradation.