It can be hyperphosphorylated further in vitro (“NTP”) by incubation with a crude rat brain extract, as shown for example by the acquisition of immunoreactivity recognized by the phosphorylation-dependent mAb 21/D10 raised against the A68 preparation of sarkosyl-insoluble tau from AD brain [9] (Figure 1c). This evidence concerns the gene MAPT and Alzheimer disease.