We also used APN-1607 (also known as PM-PBB3), a PET tracer known to fluorescently label various aggregates tau species but not monomeric tau.54,55 We found significant fluorescence labeling in the CA1 region of 22-month-old AppNL-G-F rat brain, similar to that in 3× Tg-AD mice (positive control) (Fig. 2j). This evidence concerns the gene MAPT and Alzheimer disease.