Fig. 5.

Dosage effect model for normal and pathogenic tau action. Cell function and viability require properly regulated MT dynamics. Overly suppressed dynamics, such as those that occur in the presence of taxol and, as we propose, might occur in the FTDP-17 RNA splicing mutations, result in cell death. Similarly, overly dynamic MTs, such as those that occur in taxol-resistant and -dependent cells in the absence of taxol (16) and those that might occur in the FTDP-17 missense mutations and in cells expressing hyperphosphorylated tau, also result in cell death.